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PA10 should be low or high durying boot? #13

Closed 1983FFly closed 8 years ago

1983FFly commented 8 years ago

In datasheet of STM32F405xx 2.2.13: The boot loader is located in system memory. It is used to reprogram the Flash memory by using USART1 (PA9/PA10), USART3 (PC10/PC11 or PB10/PB11), CAN2 (PB5/PB13), USB OTG FS in Device mode (PA11/PA12) through DFU (device firmware upgrade).

PA10: USART1_RX pull up by R21 100k PB11: USART3_RX pull up by R12 4k7 PC11: USART3_RX pull up by R13 100k

PB5: CAN2_RX pull down by R20 100k PB2: BOOT1 pull down by R14 100k

In PYBv10b.pdf USB DFU requires stable levels on PA10, PB5, PB11 & PC11. PB2 must be low during boot. R12, R13, R20 & R21 provide stable input levels for DFU.

dpgeorge commented 8 years ago

PA10 must be stable during boot. It can be high or low, as long as it's a stable logic level. On pyboard it's pulled high.

1983FFly commented 8 years ago

Thank you! I am designing a copy for PYBv10b with: 1:size 50mm x 50mm; 2:use 0805 resistor & capacitor; 3:change some small components to lager packaging。 This coyp is easy for rookie to make and test.