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| 1 ========================================== | |
| 2 HP 34970A Data Acquisition Unit - part 6 | |
| 3 ========================================== | |
| 4 | |
| 5 | |
| 6 :Author: David Douard | |
| 7 :Category: Electronics | |
| 8 :Tags: HP, 34970A, HP34970A, DMM, repair, test equipment | |
| 9 :series: HP 34970A repair | |
| 10 :series_index: 6 | |
| 11 | |
| 12 | |
| 13 Quick follow up; I recently got back on this project to try to complete it and fix | |
| 14 remaining problems. | |
| 15 | |
| 16 The source code for the firmware is available here: | |
| 17 | |
| 18 https://hg.sdfa3.org/hp34970-firmware | |
| 19 | |
| 20 The Kicad project is available here: | |
| 21 | |
| 22 https://hg.sdfa3.org/hp34970-pcb | |
| 23 | |
| 24 | |
| 25 Making the USBDevice work | |
| 26 ========================= | |
| 27 | |
| 28 As described in the `previous episode <{filename}/hp34970a_5.rst>`_, I could not make | |
| 29 the USBDevice of the STM32F303RD work with `mbed-os <https://os.mbed.com/>`_ framework I | |
| 30 use to write the firmware. | |
| 31 | |
| 32 The `STM32F303RD | |
| 33 <https://www.st.com/en/microcontrollers-microprocessors/stm32f303rd.html>`_ is not yet | |
| 34 officially supported by mbed-os (mainl because there is no `NUCLEO | |
| 35 <https://www.st.com/en/evaluation-tools/stm32-nucleo-boards.html>`_ board with | |
| 36 this CPU. | |
| 37 | |
| 38 However the STM32F303RE is supported, at least partially. For example, the USBDevice is | |
| 39 not working at all in the latest version of mbed-os (6.15.0). But some `work has been | |
| 40 done recently <https://github.com/ARMmbed/mbed-os/pull/15116>`_ to enable USB_DEVICE on | |
| 41 CPUs of the STM32F3 family. But this last PR was not enoght to make the USB device work; | |
| 42 I have submitted a `PR <https://github.com/ARMmbed/mbed-os/pull/15132>`_ that needs to | |
| 43 be merged to make the USB device actually work. | |
| 44 | |
| 45 Also, the difference between the 2 being (as far as I know) only the size of the flash size | |
| 46 (384KB vs. 512 KB). | |
| 47 | |
| 48 So I had 3 problems to solve: | |
| 49 | |
| 50 - compile the code for a custom board using the mbed framework in platformio, | |
| 51 - use a custom CPU decription, | |
| 52 - use a patched version of the latest version of mbed-os in platformio (while the | |
| 53 officially supported version at this moment is only the 6.9.0). | |
| 54 | |
| 55 | |
| 56 Custom version of mbed in platformio | |
| 57 ------------------------------------ | |
| 58 | |
| 59 Using a custom version of a framework (here mbed) in platformio is not properly | |
| 60 documented. But thanks to `the response | |
| 61 <https://community.platformio.org/t/support-for-mbed-os-6-stable-and-mature-apis-cloud-services-support-enhancements-to-the-bare-metal-profile/15079/9>`_ | |
| 62 to my question on the `platformio forum <https://community.platformio.org/>`_, I could | |
| 63 make it work. Obviously, I submitted `a PR | |
| 64 <https://github.com/platformio/platformio-docs/pull/214>`_ to `platformio-docs | |
| 65 <https://github.com/platformio/platformio-docs>`_. | |
| 66 | |
| 67 So now I have my (more or less) `up to date repository | |
| 68 <https://github.com/douardda/platformio-framework-mbed>`_ usable as `platform_packages` | |
| 69 config argument. | |
| 70 | |
| 71 Custom board and CPU description | |
| 72 -------------------------------- | |
| 73 | |
| 74 This part I am not completely sure how it should be done. There are actually 2 parts: | |
| 75 - tell mbed about the CPU description, | |
| 76 - tell platformio about is and use it. | |
| 77 | |
| 78 The platformio part is `documented here | |
| 79 <https://docs.platformio.org/en/latest/platforms/creating_board.html>`_ | |
| 80 | |
| 81 It mostly consists in creating a json file in the `boards/` directory of the platformio | |
| 82 project directory. | |
| 83 | |
| 84 For this project, I used the description of the NUCLEO_F303RE as starting point. The | |
| 85 file is `boards/hp34970_fp_f303rd.json | |
| 86 <https://hg.sdfa3.org/hp34970-firmware/file/tip/boards/hp34970_fp_f303rd.json>`_ in the | |
| 87 `firmware source code repository <https://hg.sdfa3.org/hp34970-firmware/>`_. | |
| 88 | |
| 89 Once the board is described, it can be used in the `platformio.ini` file: | |
| 90 | |
| 91 .. code-block:: bash | |
| 92 | |
| 93 ~/e/hp34970-firmware$ pio boards | grep hp34 | |
| 94 hp34970_fp_f303rd STM32F303RDT7 72MHz 384KB 64KB HP34970 Replace Front Panel Board (STM32F303RD, 64k RAM, 384k Flash) | |
| 95 | |
| 96 | |
| 97 | |
| 98 Then we need to tell mbed about this board. This is `documented there | |
| 99 <https://os.mbed.com/docs/mbed-os/v6.15/porting/porting-custom-boards.html>`_ | |
| 100 | |
| 101 It is a matter of creating a `custom_targets.json` file with the board description. | |
| 102 Again, I used the existing NUCLEO_F303RE as starting point, then added/removed what I | |
| 103 needed for this project: | |
| 104 | |
| 105 .. code-block:: json | |
| 106 | |
| 107 { | |
| 108 "HP34970_FP_F303RD": { | |
| 109 "inherits": [ | |
| 110 "MCU_STM32F303xE" | |
| 111 ], | |
| 112 "overrides": { | |
| 113 "clock_source": "USE_PLL_HSE_XTAL" | |
| 114 }, | |
| 115 "device_has_add": [ | |
| 116 "USBDEVICE" | |
| 117 ], | |
| 118 "mbed_rom_size": "0x60000", | |
| 119 "bootloader_supported": true, | |
| 120 "device_name": "STM32F303RE" | |
| 121 } | |
| 122 } | |
| 123 | |
| 124 Then the actual description (pins, memory config, etc.) are C files put in a | |
| 125 `TARGET_HP34970_FP_F303RD` directory. Here again, started from files copied from the | |
| 126 `STM32F303xE target | |
| 127 <https://github.com/ARMmbed/mbed-os/tree/master/targets/TARGET_STM/TARGET_STM32F3/TARGET_STM32F303xE>`_. | |
| 128 | |
| 129 | |
| 130 End result | |
| 131 ========== | |
| 132 | |
| 133 It took me some time, but in the end, I finally got a firmware that works OK, including | |
| 134 a working USB serial port. For now, this serial connection is still used only for | |
| 135 debugging purpose (and firmware upload in DFU mode), but it may be improved in the | |
| 136 future, if needs be. | |
| 137 | |
| 138 So I could put the HP34970A back together (at last). I drilled a couple of small holes | |
| 139 for the Reset and DFU buttons and a (not so) square hole for the USB plug in the blue | |
| 140 glass. | |
| 141 | |
| 142 The result looks very decent to me: | |
| 143 | |
| 144 .. image:: {static}/images/hp34970a/finished.jpg | |
| 145 :alt: finished look of the device with the replacement front panel | |
| 146 :class: image-process-large-photo | |
| 147 | |
| 148 .. peertube:: 14d0e7e2-74d5-44fe-90e9-d6b102ae01a1 |
