Pierre David / Encoder_Nucleo_32_bits

32bits encoder counter using 16bits TIM and a 32bits software counter

Dependents:   v1 v2 v2bis GestionPixy ... more

Software 32 bits quadrature encoder interface for STM32 targets

This library is designed to help interface quadrature encoders with STM32 targets. The base idea is to use a timer as a counter with several inputs corresponding to the A and B channels of a quadrature encoder. This is easily done with the new STM32 chips from STMicro, and of course with the Nucleo Boards.

Almost every Nucleo Board has 4 or 5 of those interfaces, that can be routed to several pins (I still have to check with every board to this day). This library provides an easy way to use these quadrature decoders, with an added feature : using software 32 bits integers to stock the counter, allowing a more efficient way to use them. In deed, most of the timers of the Nucleo Boards are 16 bits counters, and thus can limit the possibilities in some projects.

The solution provided here uses the update interrupt of the timer, set when the counter over- or underflows, and updates an 32 bits integer accordingly, allowing to track the encoder activity on a range of -(2^31) to (2^31)-1, or -2147483648 to 2147483647.

Plus, this interface allows to use a simple object, easily instantiated.

Example code

#include "mbed.h"
#include "Nucleo_Encoder_16_bits.h"


Nucleo_Encoder_16_bits encoder1(TIM3);

void main (void)
{
    printf("Start of Nucleo Encoder test program");

    for(;;)
    {
        wait(1.0);
        printf("Encoder count : %l", encoder1.GetCounter());
    }
}

Please check the header file corresponding to your target to get the physical pins to which you have to connect the signals (EncoderMspInitxx.h)

Also, please do not mind the name of the files or objects/methods in this library. Some are named "16 bits", but everything runs using 32 bits soft counters, as said above.

EncoderMspInitL4.cpp

Committer:
kkoichy
Date:
2016-05-26
Revision:
1:e82009479b5c
Parent:
0:ebd170807e11

File content as of revision 1:e82009479b5c:

#include "mbed.h"
/*
 * HAL_TIM_Encoder_MspInit()
 * Overrides the __weak function stub in stm32f4xx_hal_tim.h
 *
 * Edit the below for your preferred pin wiring & pullup/down
 * I have encoder common at 3V3, using GPIO_PULLDOWN on inputs.
 * Encoder A&B outputs connected directly to GPIOs.
 *
 * http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/DM00108832.pdf
 * Table 15 has GPIOx AFx pinouts
 *
 * TIM1_CH1: AF1 @ PA8, PE9
 * TIM1_CH2: AF1 @ PA9, PE11
 *
 * TIM2_CH1: AF1 @ PA0, PA5, PA15
 * TIM2_CH2: AF1 @ PA1, PB3
 *
 * TIM3_CH1: AF2 @ PA6, PB4, PC6, PE3
 * TIM3_CH2: AF2 @ PA7, PB5, PC7, PE4
 *
 * TIM4_CH1: AF2 @ PB6, PD12
 * TIM4_CH2: AF2 @ PB7, PD13
 *
 * TIM5_CH1: AF2 @ PA0, PF6
 * TIM5_CH2: AF2 @ PA1, PF7
 *
 */

#ifdef TARGET_STM32L4
void HAL_TIM_Encoder_MspInit(TIM_HandleTypeDef *htim)
{
    GPIO_InitTypeDef GPIO_InitStruct;

    if (htim->Instance == TIM1) {       //PA8 PA9 = Nucleo D7 D8
        __TIM1_CLK_ENABLE();
        __GPIOA_CLK_ENABLE();
        GPIO_InitStruct.Pin = GPIO_PIN_8 | GPIO_PIN_9;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
        GPIO_InitStruct.Pull = GPIO_PULLDOWN;
        GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
        GPIO_InitStruct.Alternate = GPIO_AF1_TIM1;
        HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
    }
    else if (htim->Instance == TIM2) {  //PA0 PA1 = Nucleo A0 A1
        __TIM2_CLK_ENABLE();
        __GPIOA_CLK_ENABLE();
        GPIO_InitStruct.Pin = GPIO_PIN_0 | GPIO_PIN_1;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
        GPIO_InitStruct.Pull = GPIO_PULLDOWN;
        GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
        GPIO_InitStruct.Alternate = GPIO_AF1_TIM2;
        HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
    }
    else if (htim->Instance == TIM3) {  //PB4 PB5 = Nucleo D5 D4
        __TIM3_CLK_ENABLE();
        __GPIOB_CLK_ENABLE();
        GPIO_InitStruct.Pin = GPIO_PIN_4 | GPIO_PIN_5;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
        GPIO_InitStruct.Pull = GPIO_PULLDOWN;
        GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
        GPIO_InitStruct.Alternate = GPIO_AF2_TIM3;
        HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
    }
    else if (htim->Instance == TIM4) { // PB6 PB7 = Nucleo D10 MORPHO_PB7
        __TIM4_CLK_ENABLE();
        __GPIOB_CLK_ENABLE();
        GPIO_InitStruct.Pin = GPIO_PIN_6 | GPIO_PIN_7;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
        GPIO_InitStruct.Pull = GPIO_PULLDOWN;
        GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
        GPIO_InitStruct.Alternate = GPIO_AF2_TIM4;
        HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
    }
    else if (htim->Instance == TIM5) { // here for completeness, mbed sytem timer uses this
        __TIM5_CLK_ENABLE();
        __GPIOA_CLK_ENABLE();
        GPIO_InitStruct.Pin = GPIO_PIN_0 | GPIO_PIN_1;
        GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
        GPIO_InitStruct.Pull = GPIO_PULLDOWN;
        GPIO_InitStruct.Speed = GPIO_SPEED_HIGH;
        GPIO_InitStruct.Alternate = GPIO_AF2_TIM5;
        HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
    }
}
#endif