Africa's Talking Eris v1 Dev Kit HC-SR04 Sample

TLDR;

To get up and running quickly with this sample, follow the steps below:

1. Hook the HC-SR04 Sensor to PB10 {trigger} and PB11 {echo} pins on the board

2. Flash ./Dist/ultrasonic.bin in to your dev kit.

3. Open Serial to view data

For a detailed write up, read below

Pinout Configuration

• See overrall config as shown below

• Set PB10 to GPIOOutput as shown

• Set PB11 to GPIOInput as shown

• Set HSE to Crystal/Ceramic Resonator and disable LSE as shown

• Under timer config set Clock Source to Internal Clock for TIM1.

• Set prescaler value to 72 - 1 and ARR to 0xffff - 1.

• Set serial mode to Asynchronous for both USART1 and USART2 and ensure gloabl interrupt is enabled under NVIC Settings

Clock Configuration

• See below clock configuration.

  • Toggle PLL and PLLCLK
  • Set input frequency to 8Mhz

• You might want to set the multiplier PLLMul to 11 or above then click Resolve Clock Issues

Project Management

• Under Project Manager ensure Generate peripheral initialization... is checked

• Then inside Advanced Settings Set USART driver to LL
  

SAVE AND GENERATE PROJECT

Library Config

• Inside ./Core/Inc/main.h ensure you have the following under Private defines .

#define TRIGGER_PIN GPIO_PIN_10  

#define TRIGGER_PORT GPIOB 

#define ECHO_PIN GPIO_PIN_11 

#define ECHO_PORT GPIOB

Important Others

• Note that the line shown below is commented under ./Core/Src/syscalls.c

extern int __io_putchar(int ch) __attribute__((weak)); 

• Also note that an IRQ handler is required for USART1; see ./Core/Src/stm32f1xx_it.c.

• Note the differences under ./Core/{*}/usart.{*}

• Note custom implementation of µSeconds delay inside ./Core/{*}/main.{*}