From 2e9dc4dad770750996824ff4534673554a5d8b5c Mon Sep 17 00:00:00 2001
From: Vincent Veron <vincent.veron@st.com>
Date: Wed, 27 Sep 2017 17:00:23 +0200
Subject: [PATCH] Use interrupt mode for I2C transfers

Switch from polling mode to IT mode for I2C transfers.
For example, this is needed if we want to use SPI and
I2C in the same time.
---
 cores/arduino/stm32/twi.c | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/cores/arduino/stm32/twi.c b/cores/arduino/stm32/twi.c
index 211afb0c82..8c3c40e5ba 100644
--- a/cores/arduino/stm32/twi.c
+++ b/cores/arduino/stm32/twi.c
@@ -255,14 +255,12 @@ void i2c_custom_init(i2c_t *obj, i2c_timing_e timing, uint32_t addressingMode, u
 
   handle->State = HAL_I2C_STATE_RESET;
 
-  if(master == 0) {
-    HAL_NVIC_SetPriority(obj->irq, 0, 1);
-    HAL_NVIC_EnableIRQ(obj->irq);
+  HAL_NVIC_SetPriority(obj->irq, 0, 1);
+  HAL_NVIC_EnableIRQ(obj->irq);
 #ifdef STM32F1xx
-    HAL_NVIC_SetPriority(obj->irqER, 0, 1);
-    HAL_NVIC_EnableIRQ(obj->irqER);
+  HAL_NVIC_SetPriority(obj->irqER, 0, 1);
+  HAL_NVIC_EnableIRQ(obj->irqER);
 #endif
-  }
 
   // Init the I2C
   HAL_I2C_Init(handle);
@@ -335,17 +333,18 @@ i2c_status_e i2c_master_write(i2c_t *obj, uint8_t dev_address,
 
 {
   i2c_status_e ret = I2C_ERROR;
-  HAL_StatusTypeDef status = HAL_OK;
-
-  // Check the communication status
-  status = HAL_I2C_Master_Transmit(&(obj->handle), dev_address, data, size, I2C_TIMEOUT_TICK);
+  uint32_t tickstart = HAL_GetTick();
 
-  if(status == HAL_OK)
+  if(HAL_I2C_Master_Transmit_IT(&(obj->handle), dev_address, data, size) == HAL_OK){
     ret = I2C_OK;
-  else if(status == HAL_TIMEOUT)
-    ret = I2C_TIMEOUT;
-  else
-    ret = I2C_ERROR;
+    // wait for transfer completion
+    while((HAL_I2C_GetState(&(obj->handle)) != HAL_I2C_STATE_READY)
+           && (ret != I2C_TIMEOUT)){
+      if((HAL_GetTick() - tickstart) > I2C_TIMEOUT_TICK) {
+        ret = I2C_TIMEOUT;
+      }
+    }
+  }
 
   return ret;
 }
@@ -379,9 +378,17 @@ void i2c_slave_write_IT(i2c_t *obj, uint8_t *data, uint8_t size)
 i2c_status_e i2c_master_read(i2c_t *obj, uint8_t dev_address, uint8_t *data, uint8_t size)
 {
   i2c_status_e ret = I2C_ERROR;
+  uint32_t tickstart = HAL_GetTick();
 
-  if(HAL_I2C_Master_Receive(&(obj->handle), dev_address, data, size, I2C_TIMEOUT_TICK) == HAL_OK) {
+  if(HAL_I2C_Master_Receive_IT(&(obj->handle), dev_address, data, size) == HAL_OK) {
     ret = I2C_OK;
+    // wait for transfer completion
+    while((HAL_I2C_GetState(&(obj->handle)) != HAL_I2C_STATE_READY)
+           && (ret != I2C_TIMEOUT)){
+      if((HAL_GetTick() - tickstart) > I2C_TIMEOUT_TICK) {
+        ret = I2C_TIMEOUT;
+      }
+    }
   }
 
   return ret;