User manual ALTIUM DESIGNER 6 - MODULE 7 - FPGA TO PCB

FPGA to PCB Training Module Software, documentation and related materials: Copyright © 2006 Altium Limited. All rights reserved. You are permitted to print this document provided that (1) the use of such is for personal use only and will not be copied or posted on any network computer or broadcast in any media, and (2) no modifications of the document is made. Unauthorized duplication, in whole or part, of this document by any means, mechanical or electronic, including translation into another language, except for brief excerpts in published reviews, is prohibited without the express written permission of Altium Limited. Unauthorized duplication of this work may also be prohibited by local statute. Violators may be subject to both criminal and civil penalties, including fines and/or imprisonment. Altium, Altium Designer, Board Insight, CAMtastic, CircuitStudio, Design Explorer, DXP, LiveDesign, NanoBoard, NanoTalk, Nexar, nVisage, P-CAD, Protel, SimCode, Situs, TASKING, and Topological Autorouting and their respective logos are trademarks or registered trademarks of Altium Limited or its subsidiaries. Microsoft, Microsoft Windows and Microsoft Access are registered trademarks of Microsoft Corporation. OrCAD, OrCAD Capture, OrCAD Layout and SPECCTRA are registered trademarks of Cadence Design Systems Inc. AutoCAD is a registered trademark of AutoDesk Inc. HP-GL is a registered trademark of Hewlett Packard Corporation. PostScript is a registered trademark of Adobe Systems, Inc. All other registered or unregistered trademarks referenced herein are the property of their respective owners and no trademark rights to the same are claimed. Module 7 Altium Designer Training FPGA to PCB FPGA to PCB Training Module 1. From FPGA to PCB....................................................................................................7-1 1.1 1.2 2. 2.1 2.2 2.3 2.4 2.5 3. 3.1 3.2 3.3 3.4 3.5 4. 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 5. 5.1 5.2 5.3 5.4 6. 6.1 6.2 7. 7.1 7.2 7.3 7.4 8. 8.1 8.2 8.3 8.4 9. 9.1 9.2 Introduction ................................................................................................ 7-1 Theory of operation .................................................................................... 7-1 Exercise 1 ­ Simulated accelerometer using a frequency generator............ 7-2 Exercise 2 ­ Simulated accelerometer using DIP-switches ......................... 7-3 Exercise 3 ­ Simulated accelerometer using an IOB................................... 7-3 Exercise 4 ­ Test with real accelerometer................................................... 7-4 Exercise 5 ­ Test with complete software ................................................... 7-5 Which device will fit my design?.................................................................. 7-7 Building for a foreign device........................................................................ 7-8 Flexible configurations .............................................................................. 7-10 Exercise 6 ­ Build for a foreign device ...................................................... 7-11 Exercise 7 ­ Squeezing the design ........................................................... 7-11 Understanding the document stack........................................................... 7-14 Using the FPGA to PCB project wizard ..................................................... 7-16 Choosing the FPGA configuration............................................................. 7-16 Initial FPGA pin assignments.................................................................... 7-17 Choosing the target PCB project............................................................... 7-19 Configuring the FPGA component schematic sheet .................................. 7-19 Configuring the sheet symbol schematic sheet ......................................... 7-20 Exercise 8 ­ Running the FPGA to PCB project wizard............................. 7-21 Modifying the auto generated sheet .......................................................... 7-24 A word about special function FPGA pins ................................................. 7-24 Recreating the autogenerated sheet ......................................................... 7-24 The FPGA workspace map....................................................................... 7-25 The synchronize dialog............................................................................. 7-26 Synchronizing matched signals................................................................. 7-28 Synchronizing unmatched signals............................................................. 7-29 Configuring I/O standards ......................................................................... 7-32 Exercise 9 ­ Using the FPGA signal manager........................................... 7-33 Supported devices.................................................................................... 7-36 Creating the link ....................................................................................... 7-36 Linking an auto generated sheet to an existing PCB project...................... 7-39 Exercise 10 ­ Manually linking a PCB and FPGA project .......................... 7-39 Pin swapping in the PCB document .......................................................... 7-40 Pin swapping in the FPGA project ............................................................ 7-46 Pin swapping in both PCB and FPGA projects .......................................... 7-47 Exercise 11 ­ Pin swapping...................................................................... 7-47 Exercise 12 ­ Migration stage 1................................................................ 7-49 Exercise 13 ­ Migration stage 2................................................................ 7-51 i Enhancing development through component emulation......................................7-2 Migrating to an alternate FPGA device ...................................................................7-7 From FPGA project to PCB project .......................................................................7-14 Maintaining project synchronization.....................................................................7-25 Configuring FPGA I/O .............................................................................................7-32 Manually linking FPGA and PCB projects ............................................................7-35 Pin swapping ...........................................................................................................7-40 Commissioning the design.....................................................................................7-49 Altium Designer Training Module FPGA to PCB 9.3 9.4 9.5 10. Exercise 14 ­ Calibration.......................................................................... 7-51 Exercise 15 ­ Bootstrapping the FPGA..................................................... 7-51 Exercise 16 ­ Reverting to test mode ....................................................... 7-53 Review ......................................................................................................................7-54 7 - ii Altium Designer Training Module FPGA to PCB 1. From FPGA to PCB 1.1 Introduction The NanoBoard is a tremendously powerful embedded platform that can dramatically decrease prototyping efforts and time-to-market. Although some designs may make use of the NanoBoard in the final design, Altium recognize that most designs will need to be transferred from the NanoBoard and onto a custom production board. DXP provides a number of features that assist in the migration of designs to production ready PCBs and this shall be the focus of today's activities. Over the course of today we will take a typical embedded project and follow its development from the working prototype stage through to the fully implemented production PCB. The case study we have chosen is a Digital Spirit Level. 1.2 Theory of operation The digital spirit level contains a MEMS based accelerometer capable of measuring acceleration up to ±2G across two perpendicular axes. Because acceleration due to gravity is known to be a relative constant of 9.8m/s2, we can use trigonometry to calculate the tilt angle of the accelerometer. cos = a / 9.8 therefore: = cos-1(a / 9.8) where a = acceleration experienced by the accelerometer = tilt angle of accelerometer. An accelerometer is most sensitive to tilt when its sensitive axis is perpendicular to the force of gravity, i.e., parallel to the earth's surface. At this orientation its sensitivity to changes in tilt is highest. When the accelerometer is oriented on axis to gravity, i.e., near its +1 g or ­1 g reading, the change in output acceleration per degree of tilt is negligible. When the accelerometer is perpendicular to gravity, its output will change nearly 17.5 mg per degree of tilt, but at 45° degrees it is changing only at 12.2 mg per degree and resolution declines. The 2-axis accelerometer located on the DSL is oriented so that the X and Y axes are in the same plane as the PCB i.e. the X-axis points along the long dimension of the PCB and the Y-axis points along the short dimension. A "bubble" is displayed on the LCD to emulate the operation of a traditional Spirit Level. 9.8 a Figure 1. Accelerometer location on the spirit level PCB. 7-1 Altium Designer Training Module FPGA to PCB 2. Enhancing development through component emulation Often during development it is desirable to begin software development prior to a hardware platform being fully available. This was true when developing this training case study. We had the concept of what it was we wished to build but the accelerometer was some way off being delivered. Rather than delay software development until it arrived, we made use of the flexible FPGA environment to build a simulated accelerometer. By creating a custom piece of hardware that simulated the PWM characteristic of the actual accelerometer, we were able to continue software development and tune our application under very controlled conditions. 2.1 Exercise 1 ­ Simulated accelerometer using a frequency generator To get started quickly, the easiest way to generate an oscillating digital signal is to use a frequency generator. Although this will not give us control over the mark/space ratio, it does allow for control over the period of the signal. A complete project has been created in preparation for this exercise. Your instructor will tell you where to find it on your local hard drive. 1. Open the SpiritLevel.PRJFPG project as directed by your instructor. 2. Observe the contents of the schematic document SL_FPGA_FrqGen.SchDoc. U3 CLK_BRD U4 U6 CLK VCC INIT OR2N1S GND Reset CLK RST EA SFRDATAO[7..0] SFRDATAI[7..0] SFRADDR[6..0] SFRWR SFRRD P0O[7..0] P0I[7..0] P1O[7..0] P1I[7..0] P2O[7..0] P2I[7..0] P3O[7..0] P3I[7..0] DELAY[7..0] FPGA_STARTUP8 U1 CLK DIN[7..0] DOUT[7..0] ADDR[11..0] WE [11..0] U9 FREQ INV [11..0] RAMS_8x4K U7 TIMEBASE ROMDATAO[7..0] ROMDATAI[7..0] MEMDATAO[7..0] MEMDATAI[7..0] ROMADDR[15..0] ROMWR MEMADDR[15..0] ROMRD MEMWR MEMRD INT0 PSWR INT1 PSRD T0 T1 Frequency Generator CLKGEN GND RXD TXD RXDO TSK51A OCD Microprocessor TSK51A_D Figure 2. Using a frequency generator to simulate an accelerometer input 3. Build the design and download it to the NanoBoard. 4. Set the NanoBoard Clock to 50MHz and the frequency generator to 1Khz. 5. Observe the output on the LCD. The bottom row of the LCD should show two variables being updated; T1 and T2. These are the calculations made by the timer routine for the corresponding T1 and T2 time intervals defined on the accelerometer datasheet. 7-2 Altium Designer Training Module FPGA to PCB 6. Set the frequency of the clock generator to a value around 1KHz. Because we are sending a 50% duty cycle signal to the processor, T2 should be almost exactly double T1. 7. Save your work. It will be used for the basis of the next couple of exercises. 2.2 Exercise 2 ­ Simulated accelerometer using DIP-switches The next step will make use of the PWM circuit developed in Exercise 1 of Day 1. This circuit operates at a fixed frequency but now we have control over the mark / space ratio. 1. Before doing any modifications, save SL_FPGA_FrqGen.SchDoc as SL_FPGA_PWM.SchDoc. 2. Modify SL_FPGA_PWM.SchDoc to include the PWM circuit instead of the Frequency Generator as shown in Figure 3. U3 P182 P3 CLK_BRD TEST_BUTTON CLK_BRD U4 U6 CLK VCC INIT OR2N1S GND Reset CLK RST EA SFRDATAO[7..0] SFRDATAI[7..0] SFRADDR[6..0] SFRWR SFRRD P0O[7..0] P0I[7..0] P1O[7..0] P1I[7..0] P2O[7..0] P2I[7..0] DELAY[7..0] FPGA_STARTUP8 U1 CLK DIN[7..0] DOUT[7..0] ADDR[11..0] WE [11..0] U9 INV GT LT GND [11..0] RAMS_8x4K U7 VCC U12 CB8CEB Q[7..0] U8 A[7..0] B[7..0] COMPM8B P3O[7..0] P3I[7..0] ROMDATAO[7..0] ROMDATAI[7..0] MEMDATAO[7..0] MEMDATAI[7..0] ROMADDR[15..0] ROMWR MEMADDR[15..0] ROMRD MEMWR MEMRD INT0 PSWR INT1 PSRD T0 T1 RXD TXD RXDO TSK51A OCD Microprocessor TSK51A_D CLK_BRD CDIV256 / 256 CE C CEO TC CLR ON SW[7..0] 1 23 4 56 78 U11 P63,P64,P68,P69,P70,P71,P73,P74 CLK_BRD FREQA FREQB TIMEBASE Frequency Counter FRQCNT2 Figure 3. Using DIP switches and PWM circuit to simulate the operation of the accelerometer 3. Build the design and download it to the NanoBoard. 4. Set the NanoBoard Clock to 50MHz and ensure that at least one of the NanoBoard DIP switches is set to ON. 5. Observe the output on the LCD and the Frequency Counter. Flip some of the DIP-switches and see that the LCD display reflects the change in the mark-to-space ratio. 6. Save your work. 2.3 Exercise 3 ­ Simulated accelerometer using an IOB Without laboring the point about simulated circuits too much, there may be situations where it is not convenient to consume hardware resources such as the DIP-switches to simulate a circuit's operation. It is here that the control afforded by the NanoBoard is such a great asset. 1. Before doing any modifications, save SL_FPGA_PWM.SchDoc as SL_FPGA_PWM_IOB.SchDoc. 2. Modify SL_FPGA_PWM_IOB.SchDoc by removing the DIP switches and replace them with a digital IOB module. 3. Build the design and download it to the NanoBoard. 7-3 Altium Designer Training Module FPGA to PCB U7 VCC U11 CLK_BRD Q[7..0] CE C CEO TC CLR CB8CEB U13 AIN[7..0] AOUT[7..0] U8 A[7..0] B[7..0] COMPM8B GT LT / 256 CDIV256 4. Set the NanoBoard Clock to 50MHz. 5. Open the IOB controller in the devices view and set / clear some of the bits. Observe that the LCD display reflects the change in the mark-to-space ratio. 6. Save your work. 1 Ch x 8 Bit Digital IO IOB_1X8 Figure 4. Using an IOB as part of a simulated accelerometer 2.4 Exercise 4 ­ Test with real accelerometer In this final step, we will finally connect a real accelerometer to the NanoBoard and test our design with this. The accelerometer that we will be using is the one contained on the Spirit Level board. 1. Before doing any modifications, save SL_FPGA_PWM_IOB.SchDoc as SL_FPGA_Accel.SchDoc. 2. Modify SL_FPGA_Accel.SchDoc by removing the PWM circuit and IOB block entirely and replacing them with an input port connection to `HA3'. U3 P182 P3 CLK_BRD TEST_BUTTON CLK_BRD U4 U6 CLK VCC INIT OR2N1S GND Reset CLK RST EA SFRDATAO[7..0] SFRDATAI[7..0] SFRADDR[6..0] SFRWR SFRRD P0O[7..0] P0I[7..0] P1O[7..0] P1I[7..0] P2O[7..0] P2I[7..0] DELAY[7..0] FPGA_STARTUP8 U1 CLK DIN[7..0] DOUT[7..0] ADDR[11..0] WE [11..0] U9 INV [11..0] RAMS_8x4K HA3 P3O[7..0] P3I[7..0] ROMDATAO[7..0] ROMDATAI[7..0] MEMDATAO[7..0] MEMDATAI[7..0] ROMADDR[15..0] ROMWR MEMADDR[15..0] ROMRD MEMWR MEMRD INT0 PSWR INT1 PSRD T0 T1 GND RXD TXD RXDO TSK51A OCD Microprocessor TSK51A_D U12 FREQA FREQB CLK_BRD TIMEBASE Frequency Counter FRQCNT2 Figure 5. Connecting to a real accelerometer 3. Using a 20-pin ribbon cable, connect HDR2 on the target board to USER HEADER A on the NanoBoard. Do not connect the USER BOARD connector (10-pin ribbon cable) at this point. 4. Ensure the `X-Axis' jumper is installed. 5. Power up the target board. The accelerometer on the target board will supply the accelerometer signal to the NanoBoard. 6. Open the Devices view. Build, download and run the project on the NanoBoard. 7. Observe the LCD output as the target board is tilted. 7-4 Altium Designer Training Module FPGA to PCB 2.5 Exercise 5 ­ Test with complete software Having verified the operation of our LCD interface and accelerometer circuit, we can now proceed to completing the entire application software. A complete project has been created in preparation for this exercise. You will find it in ..\Shell\Day 3\Exercise 5. 1. Observe the contents of the schematic document SL_FPGA_Complete.SchDoc. Note that this sheet contains all possible configurations for our test circuit (Figure 6). 2. Using a 20-pin ribbon cable, connect HDR2 on the target board to USER HEADER A on the NanoBoard. Do not connect the USER BOARD connector (10-pin ribbon cable) at this point. 3. Ensure the X axis jumper is in place on the target board. 4. Power up the target board. The accelerometer on the target board will supply the accelerometer signal to the NanoBoard. 5. Open the Devices view. Build, download and run the project on the NanoBoard. 6. Observe the LCD output as the target board is tilted. 7. Open the digital IOB control panel. Assert bit 02 and 01. Observe the LCD panel as you slowly toggle bit 00. Satisfy your understanding of this circuit by looking at the schematic. 7-5 Altium Designer Training Module FPGA to PCB JTAG JTAG JTAG JTAG JTAG . . . JTAG TDI TDO TCK TMS JTAG_NEXUS_TDI JTAG_NEXUS_TDO JTAG_NEXUS_TCK JTAG_NEXUS_TMS P8 P11 P9 P10 TRST VCC Processor Clock should be set to 50MHz PROCESSOR_CLOCK U_PROC FREQ P182 CLK_BRD CLK_BRD TIMEBASE Frequency Generator CLKGEN U2 U3 [7..0] LCD_LIGHT LCD_E LCD_RW LCD_RS LCD_DB[7..0] 2 x 16 Liquid Crystal Display P94 P89 P166 P164 P88,P87,P86,P84,P83,P82,P81,P75 U4 [7..0] Reset GND I[7..0] U5 IOBUF8B LEDS[7..0] P0O[7..0] P0I[7..0] P1O[7..0] P1I[7..0] P2O[7..0] P2I[7..0] P3 U6 CLK VCC FPGA_STARTUP8 U1 CLK PROG_ADDR[11..0] [11..0] [11..0] U9 U17 INV T0 T1 S0 TEST_BUTTON INIT OR2N1S SFRADDR[6..0] SFRWR SFRRD J8B_8S LEDS[7..0] P55,P56,P57,P58,P59,P60,P61,P62 U10 SFRDATAO[7..0] SFRDATAI[7..0] CLK RST EA DELAY[7..0] ROMADDR[15..12] DIN[7..0] DOUT[7..0] ADDR[11..0] WE ROMADDR[15..0] O0 O1 O2 O3 O4 O5 O6 O7 RAMS_8x4K P3O[7..0] P3I[7..0] ROMDATAO[7..0] ROMDATAI[7..0] MEMDATAO[7..0] MEMDATAI[7..0] ROMADDR[15..0] ROMWR MEMADDR[15..0] ROMRD MEMWR MEMRD INT0 PSWR INT1 PSRD MEMADDR[15..0] [10..0] MEMADDR[11..0] HA3_IN D0 D1 DIN[7..0] DOUT[7..0] RAM_ADDR[10..0] [10..0] ADDR[10..0] WE RAMS_8x2K CLK GND M1_S2S1 RXD TXD RXDO TSK51A OCD Microprocessor TSK51A_D PROCESSOR_CLOCK PWM Clock should be set to 100KHz U7 CLK CLK_CAP CHANNELS[7..0] TRIGGER Logic Analyser LAX_1K8 STATUS U_PWMCLK TIMEBASE Reset UpX DownX VHDLENTITY: PWM Frequency Generator CLKGEN FREQ Clk Reset OutX XSampleInput U_PWM PWM.Vhd HB3_OUT HB5_OUT I0 U18 O[7..0] I1 I2 I3 I4 I5 I6 I7 J8S_8B U12 FREQA FREQB PROCESSOR_CLOCK TIMEBASE VCC U19 U20 HB3_OUT HA3_IN IOBUF ON U15 I[7..0] U8 U11 INV AND2S AND2S U14 U13 Frequency Counter FRQCNT2 1 23 45 67 8 SW[7..0] AIN[7..0] AOUT[7..0] P63,P64,P68,P69,P70,P71,P73,P74 1 Ch x 8 Bit Digital IO IOB_1X8 IOBUF O0 O1 O2 O3 O4 O5 O6 O7 U21 HB5_OUT J8B_8S IO_0 Increases/Decreases the PWM Threshold pt. IO_1 Selects whether I0_0 is active IO_2 Selects input to micro (0 = accelerometer on HA3, 1 = PWM) HA2 HA3 HA4 HA5 HA6 HA7 HA8 HA9 HA10 HA11 HA12 HA13 HA14 HA15 HA16 HA17 HA18 HA19 HA2 HA3 HA4 HA5 HA6 HA7 HA8 HA9 HA10 HA11 HA12 HA13 HA14 HA15 HA16 HA17 HA18 HA19 P110 P111 P112 P113 P114 P115 P116 P120 P121 P122 P123 P125 P126 P127 P21 P22 P23 P24 IOBUF HB2 HB3 HB4 HB5 HB6 HB7 HB8 HB9 HB10 HB11 HB12 HB13 HB14 HB15 HB16 HB17 HB18 HB19 HB2 HB3 HB4 HB5 HB6 HB7 HB8 HB9 HB10 HB11 HB12 HB13 HB14 HB15 HB16 HB17 HB18 HB19 P27 P29 P30 P31 P33 P34 P35 P36 P40 P41 P42 P43 P44 P45 P46 P47 P48 P49 Figure 6. Complete Spirit Level FPGA schematic. 7-6 Altium Designer Training Module FPGA to PCB 3. Migrating to an alternate FPGA device Up until now, the default daughter-board constraint file has provided adequate information to get our project up and running on the NanoBoard. But what if our final design wishes to make use of a device that is not available for the NanoBoard? 3.1 Which device will fit my design? This is a common question for most designs. The development work has been largely completed on a prototyping platform and the resource requirements are well understood. How do we go about selecting the smallest / cheapest device capable of supporting our design? 3.1.1 Determining resource requirements Ultimately all designs will need to be built and tested on their intended target device but there are a few things we can do to speed up the process of identifying candidate devices. If you already have a design that has been built and tested for one of the NanoBoard daughter boards then a Place and Route report file will have been generated. You should be able to find it using the storage manager Figure 7. Locating the place and route (.PAR) report file from the storage manager. Open the .PAR file in the text editor by double-clicking it. Locate the section within it that says Device utilization summary. Here you will find a summary of the key resources used by the design. Device utilization summary: Number of External GCLKIOBs Number of External IOBs Number of LOCed External IOBs Number of BLOCKRAMs Number of SLICEs Number of GCLKs Number of TBUFs 1 out of 4 69 out of 142 69 out of 69 15 out of 16 2481 out of 3072 2 out of 4 16 out of 3200 25% 48% 100% 93% 80% 50% 1% Figure 8. Device utilization summary contained within the place & route report file. 7-7 Altium Designer Training Module FPGA to PCB Some knowledge of the vendor tool's terminology is necessary to interpret this information but it is reasonably straightforward. Here are some of the conclusions that can be drawn from the report file: · · · · · One (1) dedicated clock pin is required Two global clock resources are required (GCLKs). 69 IOBs (input / output blocks) are consumed. We would therefore require at least 69 IO pins on our final device. 15 out of 16 BlockRAMs are consumed. On the Spartan-II family, each BlockRAM contains 512 bytes (4096 bits) of memory. Therefore our design consumes 61 Kbits of memory. 2481 SLICEs are consumed. A quick check of the Spartan-3 data sheet provides the following information: Figure 9. Spartan-3 Family Summary The XC3S50 looks like a candidate based on RAM bits and user I/O however it only contains 192 CLBs (1 CLB = 4 slices) which translates to only 4 x 192 = 768 Slices. We need at least 2481 slices or 2481 / 4 = 621 CLBs. The XC3S400 would therefore be a better choice based on the above information. We are, however, forgetting something very critical. It is not accurate to assume that the number of CLBs or Slices will be the same between device families ­ even when the devices come from the same vendor. The Spartan3 family is 1 generation newer than the Spartan-IIE family and the CLB structure has been enhanced on the Spartan3. As a result, we might just be lucky enough for our design to squeeze into a smaller Spartan3 that we originally predicted. 3.2 Building for a foreign device The FPGA build flow depicted in the Devices view will only function if the FPGA device in the hard chain matches a device in one of the project's configurations. So in order to build for a new/foreign device, we must first create a configuration with that new device in it. Creating a new configuration and specifying the device are topics that were covered on day 1. Feel free to refer back to that topic for review. A minimalist constraints file only needs to specify the part in order to be valid. At this stage we are probably not interested in taking the time to specify port mappings as we can't be totally sure that the design will fit. ;............................................................................... ;Constraints File ; Device : ; Board : ; Project : ; ; Created 16/03/2005 ;............................................................................... ;............................................................................... Record=FileHeader | Id=DXP Constraints v1.0 ;............................................................................... Record=Constraint | TargetKind=Part | TargetId=XC3S200-4TQ144C 7-8 Altium Designer Training Module FPGA to PCB Figure 10. Minimalist Constraints File 3.2.1 Changing the hard chain device If nothing is connected to the parallel port or the NanoBoard is switched off, the Devices view may present you with a window with very little apparent option for changing the device in the hard chain. The following process needs to be followed: 1. Ensure the Live checkbox is clear. This takes the NanoBoard link out of live update mode and ensures that nothing on the NanoBoard overrides the settings we are about to make. Figure 11. Adding a foreign device to the hard chain 2. Right-click in the blank region below the No Hard Device label. You should see a popup menu appear (see Figure 11). If a device is present in the Hard Chain, you can right-click on it and the same menu will appear. 3. DXP will scan the current list of constraint files in the project to build a list of device / configuration pairs. If you wish to select an alternate part, you may select the Browse option to open the Add Physical Device dialog and select a part from there. 4. If you select a device that is not currently part of a configuration, the FPGA build flow will not be enabled until a valid configuration that includes that device is created. 7-9 Altium Designer Training Module FPGA to PCB Figure 12. Selecting a device that does not have a compatible configuration Figure 13. Build Flow enabled after successfully adding foreign device to the hard chain 5. Once you have a valid device/configuration pair selected, the FPGA build flow will be enabled (Figure 13) and you can select the Build button to initiate a build. 6. Check the build report files to ensure that the design fits correctly and meets any constraints you may have specified. 3.3 Flexible configurations The key to being able to easily retargeting an FPGA project to different devices lies in the judicious use of multiple constraint files. Recall from day 1 that configurations can contain multiple constraint files. During the early stages of design migration it may not be known exactly which target FPGA device will be used in the final design. Careful partitioning of information between the constraint files will ensure that a design is easily transferable between different platforms and information duplication between configurations is minimized. 7 - 10 Altium Designer Training Module FPGA to PCB Project constraint file (SL_Project.constraint) + Target_1.constraint + Target_2.constraint ... + Target_N.constraint Target_1.PCB Target_2.PCB ... Target_3.PCB Figure 14. Using multiple constraint files. 3.3.1 Project constraint file The project constraint file will contain information that characterizes signals or ports within the design. One example is the clock port. The project constraint file will not stipulate which physical pin to be used but it will indicate that a clock resource pin should be used and that it will need to be capable of handling a certain maximum clock frequency. This information will be constant regardless of the target implementation. 3.3.2 Target constraint file The target constraint file will stipulate information that is specific to a given target implementation. For instance this file will detail the pins to be used for certain signals or ports. Creating a project constraint file early in the migration phase will help ensure synchronization across the different target implementations and will avoid duplication. The Project Constraint File will be included in all configurations and the Target Constraint File will be unique for each individual target implementation. Maintaining this level of abstraction in the design ensures that late changes are correctly propagated across all implementations in an appropriate fashion and design synchronization can be easily managed. 3.4 Exercise 6 ­ Build for a foreign device In this exercise we will build our design using a foreign device i.e. a device that we don't have a daughter board for. A partially complete project has been created in preparation for this exercise. Your instructor will tell you where to find it on your local hard drive. 1. Open the SpiritLevel.PRJFPG project used in Exercise 5. 2. Create a new constraint file and call it SizeTest.Constraint. Specify the TargetID to be a XC3S200-4TQ144C. 3. Create a new configuration called Test and include in it your newly created constraint file as well as the project constraint file (SL_Project.Constraint). 4. Open the Devices view and make sure the Live checkbox is clear. 5. Change the FPGA device to be the same as what is contained in the SizeTest.Constraint file and run the build flow. Does the design fit? 3.5 Exercise 7 ­ Squeezing the design You will have observed that our FPGA design will not fit into a XC3S200 device as it currently stands. Here is the build report that you should see in Exercise 6. 7 - 11 Altium Designer Training Module FPGA to PCB Figure 15. Trying to build a design for a device that is too small In retargeting the design we have cut the required number of Slices from 2481 (Spartan-IIE) down to 2101 (Spartan-3). Although this is a 15% improvement, our design is still too big for the device. What else can we do? We could remove a number of the test instruments contained within the design however we may wish to use these during production testing etc. so we would prefer to keep them in the design. Recall that during development we used an OCD version microcontroller as this gave us the debugging features that we required. Given that our code is now complete, now might be an appropriate time to swap to the non-OCD version microcontroller as it may just give us the savings we need. 1. Save the SL_FPGA_Complete.SchDoc as SL_FPGA_Complete_noOCD.SchDoc. 2. Replace the OCD version microcontroller with the non-OCD version. Remember to update the ChildModel1 parameter in the processor and re-link the embedded project. OCD CLK RST EA SFRDATAO[7..0] SFRDATAI[7..0] SFRADDR[6..0] SFRWR SFRRD P0O[7..0] P0I[7..0] P1O[7..0] P1I[7..0] P2O[7..0] P2I[7..0] P3O[7..0] P3I[7..0] non-OCD CLK RST EA SFRDATAO[7..0] SFRDATAI[7..0] SFRADDR[6..0] SFRWR SFRRD ROMDATAI[7..0] ROMADDR[15..0] ROMRD INT0 INT1 T0 T1 RXD TXD RXDO TSK51A Microprocessor TSK51A MEMADDR[15..0] MEMWR MEMRD PSRD P0O[7..0] P0I[7..0] P1O[7..0] P1I[7..0] P2O[7..0] P2I[7..0] P3O[7..0] P3I[7..0] MEMDATAO[7..0] MEMDATAI[7..0] ROMDATAO[7..0] ROMDATAI[7..0] MEMDATAO[7..0] MEMDATAI[7..0] ROMADDR[15..0] ROMWR MEMADDR[15..0] ROMRD MEMWR MEMRD INT0 PSWR INT1 PSRD T0 T1 RXD TXD RXDO TSK51A OCD Microprocessor TSK51A_D Figure 16. Converting to non-OCD microcontroller. 7 - 12 Altium Designer Training Module FPGA to PCB 3. Clean up any unused I/O connections. 4. Attempt to rebuild the project. Does it fit? Figure 17. Near optimal design fit. 7 - 13 Altium Designer Training Module FPGA to PCB 4. From FPGA project to PCB project At some point in the life of all designs there comes a point where they must move from the laboratory prototype to production. If a design has been successfully running on the NanoBoard, the process of migrating from an FPGA based project to a PCB based project containing the FPGA project is simplified through the use of the FPGA to PCB Project Wizard. This method automatically links the two projects and maximizes synchronization functionality between them. Project synchronization is important as it ensures that design changes made to either the PCB document or FPGA project are propagated in a controlled fashion. 4.1 Understanding the document stack Figure 18. Visualization of how the various project documents are stacked Synchronization between PCB and FPGA projects is carried out and maintained by establishing a link between the top-level ports in the FPGA project ­ specified in the relevant constraint file ­ and the corresponding pins on the FPGA component schematic. Linking is achieved using the signal name. The name given to the port in the FPGA project must be the same as the net label assigned to the corresponding pin on the schematic component in the PCB project. Figure 18 provides a visualization of how the various documents in an FPGA/PCB project stack are linked together. 7 - 14 Altium Designer Training Module FPGA to PCB FPGA_Top.SchDoc FPGA project The top level FPGA schematic document must contain ports at the point where signals are connected to physical pins on the FPGA device. The name of the ports is important as they will be used in the constraints file. FPGA.Constraint FPGA project The Constraint file defines the physical pin number that ports defined in the top level FPGA schematic will be connected to. This is referred to as a port name to FPGA pin number mapping. Port names declared in the constraint file must match those included in the top level FPGA schematic document. FPGA_Auto.SchDoc PCB project The autogenerated schematic sheet is created from information contained in the FPGA constraint file. Essentially the autosheet is a schematic representation of the port to pin mappings made by the constraint file. Port to pin connectivity on the autosheet is accomplished through the use of net labels ­ i.e. a net label is attached to wires connected to the ports on the sheet and a corresponding net label is also attached to the device pin. FPGA_Manual.SchDoc PCB project An optional `manual' sheet is generated as part of the FPGA to PCB project wizard. This manual sheet contains a sheet symbol of the autosheet ­ the ports on the autosheet are connected to corresponding ports on the sheet symbol. Connecting to this sheet symbol rather than directly to the FPGA symbol introduces an important abstraction layer. This layer facilitates easy (automated) updates to the project if the device or pin allocations should change as the project develops. TargetPCB.PCBDoc PCB project The FPGA depicted in the autosheet and abstracted on the `manual' sheet will eventuate into a physical device on the final PCB. The physical pins of this device will be connected to ports as described in the autosheet. Figure 19. The role of the various documents in the project stack 7 - 15 Altium Designer Training Module FPGA to PCB 4.2 Using the FPGA to PCB project wizard With a schematic document in the FPGA project open as the active view in the main design window, simply choose the Tools » FPGA To PCB Project Wizard entry from the menu. The wizard will appear, as shown in Figure 20: Figure 20. The FPGA To PCB project wizard. 4.3 Choosing the FPGA configuration The second page of the wizard allows you to choose the configuration that will be used for targeting the FPGA design to the PCB. The configuration uses a constraint file that defines the FPGA device to be used and its associated pin mappings. The configuration can either be an existing one that you have already defined as part of the FPGA project, or a new one, generated by the wizard. In the case of the latter, the wizard will generate a configuration and add to it a new constraint file. These will have default names (PCB Configuration and PCB Constraints.Constraint respectively) and the constraint file will be stored in the same location as the FPGA project file (*.PrjFPG), unless otherwise specified. Figure 21. Wizard-based configuration generation. The constraint file that is added to the configuration will contain a target device definition for the FPGA project, according to the device you select in the Selected Device field. You can browse for a device by clicking the ... button, to the right of the field. This will open the Choose Physical Device dialog, from where you can peruse from a number of devices available across a spectrum of FPGA vendor-device families. 7 - 16