Add Hardware Reset when Initing I2C peripheral (espressif#1201)

stickbreaker · me-no-dev · commit 1cf42702dd9f · 2018-04-06T19:13:59.000+03:00
This change uses the `_RST` bit of the i2c peripheral to force the hardware into power on reset state.  The prior code assumed the peripheral was already in a reset, it just cleared the reset bit.  

Chuck.
diff --git a/cores/esp32/esp32-hal-i2c.c b/cores/esp32/esp32-hal-i2c.c
@@ -444,11 +444,13 @@ i2c_t * i2cInit(uint8_t i2c_num, uint16_t slave_addr, bool addr_10bit_en)
 #endif
 
     if(i2c_num == 0) {
+        DPORT_SET_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG,DPORT_I2C_EXT0_RST); // I2C0 peripheral into Reset mode
         DPORT_SET_PERI_REG_MASK(DPORT_PERIP_CLK_EN_REG,DPORT_I2C_EXT0_CLK_EN);
-        DPORT_CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG,DPORT_I2C_EXT0_RST);
+        DPORT_CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG,DPORT_I2C_EXT0_RST); // Release Reset Mode
     } else {
+        DPORT_SET_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG,DPORT_I2C_EXT1_RST); // I2C1 peripheral into Reset Mode
         DPORT_SET_PERI_REG_MASK(DPORT_PERIP_CLK_EN_REG,DPORT_I2C_EXT1_CLK_EN);
-        DPORT_CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG,DPORT_I2C_EXT1_RST);
+        DPORT_CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG,DPORT_I2C_EXT1_RST); // Release Reset Mode
     }
 
     I2C_MUTEX_LOCK();
