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| − | [[Category:STM32]][[Category:STM32 Development Board]][[Category:STM32F405]][[Category:STM32 Hardware Development]]{{metadesc|Own design STM32 development board}} | + | [[Category:STM32]][[Category:STM32 Development Board]][[Category:STM32F405]][[Category:STM32 Hardware Development]]{{metadesc|Own design STM32 development board with gd32f405 mcu}} |
| | [[File:Stm32Dev rev. b - top side unpopulated.jpg|thumb|STM32Dev rev. b]] | | [[File:Stm32Dev rev. b - top side unpopulated.jpg|thumb|STM32Dev rev. b]] |
| | When designing the [[Stm32Dev - first version]] a number of mistakes was made. This lead naturally to the development of [[Stm32Dev - rev. b]]. | | When designing the [[Stm32Dev - first version]] a number of mistakes was made. This lead naturally to the development of [[Stm32Dev - rev. b]]. |
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| − | While the overall design is identical to the first version, a number of tweaks were made. These include:
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| − | * Double headers
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| − | * Different choice of [[LDO]]
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| − | * Buttons for [[NRST]] and [[Boot0]]
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| − | * 8 MHz Crystal
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| − | * Regular blue [[LED]] on PC13
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| − | * [[WS2812B]] hanging off of PC6
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| − | * SD-Card
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| − | The reasoning behind these choices should be pretty darn obvious, but let me go through them anyway.
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| − | [[File:Jumper leads on headers.jpg|thumb|Jumper leads on headers]]I absolutely positively despise breadboards. True, I might have had bad experiences because my breadboards were cheap crap, but I find myself spending more time chasing down lose connections than I do doing anything productive, so I generally much prefer just to wire stuff up using jumper leads directly on the headers. By using that approach I regularly end up in a situation where I need two leads connected to one pin, hence having a dual row is convenient.
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| − | The [[LDO]] on the original board was massively over dimensioned (can handle up to 1-2 amps). Switched that to a [https://lcsc.com/product-detail/Dropout-Regulators-LDO_Torex-Semicon-XC6206P332MR_C5446.html Torex Semicon XC6206P332MR] which will happily handle the 500 mA possible from a [[USB]] port.
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| − | Having the buttons is just a massive convenience on a development board.
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| − | The Micro-SD was added as an afterthought. There was space available and footprints are free. Since I had used it in a previous project and had a few lying around, I used the [https://lcsc.com/product-detail/Card-Sockets-Connectors_HRS-Hirose-DM3D-SF_C719027.html Hirose DM3D-SF] connector.
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| − | == Schematics ==
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| − | The full schematics is as:
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| − | [[File:Stm32dev rev. b.svg|1000px]]
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| − | As [[LDO]] regulator we are using the [https://www.torexsemi.com/file/xc6206/XC6206.pdf Torex XC6206]. It will quite happily handle around 200 mA (actually more) which is more than enough to drive a [[STM32]] and a few peripherals. The regulator is decoupled on each side with a 10 uF capacitor, which is the maximum value according to the USB specification (to prevent high inrush current which could shut down the USB port).
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| − | Two buttons are used for the [[NRST]] and [[Boot0]] pins. According to the [https://ipfs.subutai.io/ipfs/QmSFtdDUKXV7Fwd7pz4g3Qn8vM1e1kHENAxgvptZQYvmBC/DM00037051.pdf STM32F405 datasheet], the NRST is pulled up internally, so the NRST pull-up resistor is not mounted. Likewise, the Boot0 pin needs to be pulled high forcefully to trigger the bootloader, so the external pull-down on that is not mounted.
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| − | Two regular [[LED]]s are mounted on the board. One connected straight to the +3.3 V rail, and one to the PC13 GPIO pin. The use of PC13 is mainly because that seems to be a bit of a standard on development boards. The pin as such is not ideal for driving a LED as it can NOT do pulse-width modulation ([[PWM]] - see [[STM32 LED Blink]]). The choice of 1K current limiting resistors result in a fairly weak brightness (but very low current consumption).
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| − | A second RGB LED ([[WS2812B]]) is attached to PC6.
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| − | == Production Files ==
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| − | The production files are available [https://github.com/lbthomsen/stm32dev/tree/master/pcb here]. The gerber files are in stm32dev_b.zip and the bom and placement files are in stm32dev_b_bom.csv and stm32dev_b_pos.csv.
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| | == PCB == | | == PCB == |
When designing the Stm32Dev - first version a number of mistakes was made. This lead naturally to the development of Stm32Dev - rev. b.
PCB
Based on the above production files, a run of 5 boards were ordered at JLCPCB. They were received like this (and yes - we are aware of the silkscreen typo):
The USB-C connector, the SD, the ws2812 and all the headers have not been mounted by jlcpcb.
