STM32L432 Breakout

Assembled STM32L432 Breakout Board V0.1

What is it?

This is a small (37x22mm) board with an STM32L432KC6 MCU, 3.3V regulator, reset button, power LED, user GPIO LED, SWD header USB connector and all I/O pins brought out to SIP headers suitable for use in a solderless breadboard. With this board one can easily prototype small ARM Cortex Lxx applications with minimum effort and expense.

What it isn't

This is not a full development system - you'll have to gather your own programming tools, power supply, I/O devices, etc. This is not an Arduino clone with all the low-level stuff already done for you. If you want to get by on the cheap you'll have to be familiar with setting up an ARM GCC toolchain as well as using a JTAG/SWD debugger.

Features:

STM32L432KC6 CPU with:
- 32-bit ARM Cortex-M4 CPU rated for 80MHz clock
- 64kB SRAM
- 256kB Flash
- 8 Timers
- 1 QSPI
- 2 SPI
- 2 I2C
- 2 USART
- 1 LPUART
- 1 SAI
- 1 USB
- 1 CAN
- 1 CEC
- RTC
- 26 GPIO pins (4 are 5V tolerant)
- 1 12-bit SAR ADC with 10 input channels
- 2 12-bit DACs
- Op-amps, comparators, capsense
Onboard 3.3V Regulator (4.1V - 10V input range)
Filtered Analog 3.3V Supply
32kHz crystal (not required)
Power and User LEDs
Reset button
USB micro-B connector
5-pin ST-Link V2 SWD compatible programming interface
28-pin 700-mil DIP form factor (Fits solderless breadboard with 2 rows exposed on each side

Interfaces

J101, J102: 28 pins of direct access to all of the pins of the MCU. In addition a 5V input and 3.3V output as well as 2 more GND pins are available.
J103: 5-pin ST-Link V2 This connector provides the ST standard SWD debug/download connection. Note only pins 1-5 are used since this MCU doesn't provide the SWO normally present on pin 6.
J104: USB micro-B connector.
SB101/SB102: Optionally connect USB pins to SIP headers.
SW101: Reset button - tied directly to the MCU reset input. Handy way to quickly reboot your MCU after flashing new code into it.
D101: User GPIO - connected to PA2. Useful for diagnostics.
D102: Power indicator - lights up when 3.3V is present.

Software Development

The STM32 family of parts are supported by a variety of commercial IDEs, all of which are available in low-cost or limited free versions from the ST website.

I prefer to use open-source tools so I've set up a development environment based on the GNU C compiler for ARM, available for free from the Launchpad project. For downloading to the target I use OpenOCD and the ST-Link V2 SWD interface that's available on most all of the inexpensive STM32 Discovery boards. To accelerate development I also use the STM32 Standard Peripheral Library as a starting point for my code and then optimize out the heavyweight functions as required. Links to all of these are here:

Launchpad GCC: ARM-supported GCC (somewhat newer than the CS version above).
OpenOCD: JTAG/SWD interface for programming a debugging.
STM32F0 Discovery: Development board with USB flash programming and debugging.
STM32 Standard Peripheral Library for STM32F0xx: Manufacturer's low-level C driver code.

What can it do?

The STM32L432KC MCU is has excellent low power operating characteristics. I've got a home-grown bicycle computer project that couples this board with a low-res monochrome bitmapped LCD for realtime display of time, speed and distance. During operation it draws less than 1ma and when powered down it pulls only a few nano-amps.

STM32L432 Bicycle computer

Low-power Bicycle Computer based on STM32L432KC

Design Resources

Schematic: l432_bob.pdf
OSHpark board: l432_bobv0.1
Github Repo: emeb/l432_bob
More to come...

Revisions

V0.1 was first board fabbed. Note - this version is missing the 10k pulldown on the BOOT0 pin - you must bodge this on the board (see photo), or to external pin PH3.

Status

10-05-17 - Schematic and layout started.
10-16-17 - PCB design sent to fab.
11-02-17 - Assembled. Basic blinky light and USB DFU work.
05-24-18 - Web page created.

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Last Updated

:2018-05-24

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Eric Brombaugh