Pierre David
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.
Revision 1:e82009479b5c, committed 2016-05-26
- Comitter:
- kkoichy
- Date:
- Thu May 26 16:21:43 2016 +0000
- Parent:
- 0:ebd170807e11
- Commit message:
- V1.1 :; - Added one constructor with only one parameter
Changed in this revision
| Nucleo_Encoder_16_bits.cpp | Show annotated file Show diff for this revision Revisions of this file |
| Nucleo_Encoder_16_bits.h | Show annotated file Show diff for this revision Revisions of this file |
diff -r ebd170807e11 -r e82009479b5c Nucleo_Encoder_16_bits.cpp
--- a/Nucleo_Encoder_16_bits.cpp Sun May 22 19:59:18 2016 +0000
+++ b/Nucleo_Encoder_16_bits.cpp Thu May 26 16:21:43 2016 +0000
@@ -54,6 +54,51 @@
namespace mbed
{
+
+ Nucleo_Encoder_16_bits::Nucleo_Encoder_16_bits(TIM_TypeDef * _TIM)
+ {
+ TIM = _TIM;
+ // Initialisation of the TIM module as an encoder counter
+ EncoderInit(&encoder, &timer, _TIM, 0xffff, TIM_ENCODERMODE_TI12);
+
+ // Update (aka over- and underflow) interrupt enabled
+ TIM->DIER |= 0x0001;
+ // The initialisation process generates an update interrupt, so we'll have to clear the update flag before anything else
+ TIM->SR &= 0xfffe;
+
+ // Setting the ISR for the corresponding interrupt vector
+ switch((uint32_t)TIM)
+ {
+ case TIM2_BASE :
+ NVIC_SetVector(TIM2_IRQn, (uint32_t)&Overflow_Routine_TIM2);
+ NVIC_EnableIRQ(TIM2_IRQn);
+ Soft_32_Counter_TIM2 = 0;
+ break;
+
+ case TIM3_BASE :
+ NVIC_SetVector(TIM3_IRQn, (uint32_t)&Overflow_Routine_TIM3);
+ NVIC_EnableIRQ(TIM3_IRQn);
+ Soft_32_Counter_TIM3 = 0;
+ break;
+
+ case TIM4_BASE :
+ NVIC_SetVector(TIM4_IRQn, (uint32_t)&Overflow_Routine_TIM4);
+ NVIC_EnableIRQ(TIM4_IRQn);
+ Soft_32_Counter_TIM4 = 0;
+ break;
+
+ case TIM5_BASE :
+ NVIC_SetVector(TIM5_IRQn, (uint32_t)&Overflow_Routine_TIM5);
+ NVIC_EnableIRQ(TIM5_IRQn);
+ Soft_32_Counter_TIM5 = 0;
+ break;
+
+ default :
+
+ break;
+ }
+
+ }
Nucleo_Encoder_16_bits::Nucleo_Encoder_16_bits(TIM_TypeDef * _TIM, uint32_t _maxcount, uint32_t _encmode)
{
TIM = _TIM;
diff -r ebd170807e11 -r e82009479b5c Nucleo_Encoder_16_bits.h
--- a/Nucleo_Encoder_16_bits.h Sun May 22 19:59:18 2016 +0000
+++ b/Nucleo_Encoder_16_bits.h Thu May 26 16:21:43 2016 +0000
@@ -10,6 +10,7 @@
class Nucleo_Encoder_16_bits {
public :
+ Nucleo_Encoder_16_bits(TIM_TypeDef * _TIM);
Nucleo_Encoder_16_bits(TIM_TypeDef * _TIM, uint32_t _maxcount, uint32_t _encmode);
Nucleo_Encoder_16_bits(TIM_Encoder_InitTypeDef * _encoder, TIM_HandleTypeDef * _timer, TIM_TypeDef * _TIM, uint32_t _maxcount, uint32_t _encmode);
int32_t GetCounter();