STM32 - Designing an STM32L15xx board

March 15, 2016 Oliv'

Following are some notes about ST application notes I read to design an STM32L151 board.

All documents can be found here.

AN2606 - Microcontroller system memory boot mode

Voltage range
Full speed (Range 1) : 2.0 to 3.6 VDC
Capacitors:
1x100 nF by VDD pin
Min 4.7µf for the chip, 10µF recommended
Reset and power supply supervisor
Power on/down-reset signal - No consumption
Programmable voltage detector - No consumption - between 1.85 and 3.02 V, 200 mV steps. Generates an interrupt.
Brownout detector - Slight power consumption, can be disabled by option byte
Reset circuit
A 100 nF grounded capacitor is recommended, can be reduced to 10 nF
Clock
Multi-Speed Internal : Activated on reset, can be trimmed with high speed external clock.
High Speed External clock : Optional, can be clock source (<32 MHz) or oscillator (1 to 24 MHz)
Low Speed External lock : Optional, can be clock source or oscillator (32.768 kHz). [-30%; +60%} tolerances
PLL : Hook to generate various internal clocks
Clock Security System : Disable HSE if failure detected
Boot configuration : boot0 and boot1 inputs triggers 3 modes:
x0 : Flash memory
01 : System memory (ST bootloader)
11 : SRAM memory
Inline 10 k resistor is recommended
ST bootloader via USART1 or USART2
RX pin from unused USART must not be left floating