54 lines
2.1 KiB
Markdown
54 lines
2.1 KiB
Markdown
This document describes how the STM32F1 port operates and how it can be used on
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STM32-based boards, such as the "Blue Pill". STM32 MCUs are not used on any
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Arduino boards, so their restrictions aren't as widely known and less straight
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forward compared to common Arduino compatible boards. There aren't any standard
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pin mappings either.
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General considerations
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======================
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The STM32 port currently requires an 8 MHz crystal for correct operation. The
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host communication only supports a standard UART. USB serial (CDC ACM) might be
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useful for some configurations, but is unimplemented. The port is currently
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designed for and tested with STM32F103xB series MCUs, but it should work with
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any STM32F103 series MCUs with minimal changes.
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Unlike Arduino-based boards, typically there is no automatic reset on serial
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connection with STM32 boards. Please use `restart_method: command` with the
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STM32F1 port.
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Fixed pins
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==========
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When using serial, the UART used for communication with the host is
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fixed to pins PA9 (TX) and PA10 (RX). When using USB, the PA11 (D-)
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and PA12 (D+) pins are reserved. The USB code assumes that PA12 (D+)
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has a fixed pullup resistor attached to it.
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SWD pins (PA13/PA14) are enabled for debugging and cannot be used for
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any I/O. SPI uses pins PB13/PB14/PB15, but the pins can be used as
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general I/O if SPI is not used.
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Digital I/O
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===========
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All pins that aren't part of the fixed set can be used for digital I/O. Pins are
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referred to by their primary name, e.g. `PA1`. Do not try to use Arduino pin
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aliases in your configuration. See ST's datasheets for more details. The
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[STM32Duino](http://wiki.stm32duino.com/index.php?title=Blue_Pill) wiki has more
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info on the popular "Blue Pill" board.
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Analog inputs
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=============
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All ADC-capable pins can be used as analog inputs with the same naming as
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digital I/O pins. Small packages MCUs (e.g. LFQP48) have 10 channels (PA0-PA7,
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PB0-PB1), while larger package devices have 16 channels (PA0-PA7, PB0-PB1,
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PC0-PC5).
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SPI
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===
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SPI uses pin PB13 (SCK), PB14 (MISO) and PB15 (MOSI). The clock speed range is
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0.15..18 MHz. Chip select pins do not have any restrictions.
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