First version of new i2c bitbang API.

git-svn-id: https://src.develer.com/svnoss/bertos/branches/i2c@4063 38d2e660-2303-0410-9eaa-f027e97ec537

diff --git a/bertos/drv/i2c_bitbang.c b/bertos/drv/i2c_bitbang.c
index 5e9dfb0c76c8ce1ad5012dc2fccbf2bda6751045..45847c93c4e598bc2f0d66106bd110294cdaa2ed 100644 (file)
--- a/bertos/drv/i2c_bitbang.c
+++ b/bertos/drv/i2c_bitbang.c
@@ -57,7 +57,7 @@ INLINE bool i2c_bitbang_start(void)
        I2C_HALFBIT_DELAY();
        SDA_LO;
        I2C_HALFBIT_DELAY();
-       ASSERT(!SDA_IN);
+
        return !SDA_IN;
 }
 
@@ -177,3 +177,118 @@ void i2c_bitbang_init(void)
        MOD_INIT(i2c);
 }
 
+
+/*
+ * New I2C API
+ */
+
+static void i2c_bitbang_stop(struct I2c *i2c)
+{
+       SDA_LO;
+       SCL_HI;
+       I2C_HALFBIT_DELAY();
+       SDA_HI;
+}
+
+
+void i2c_bitbang_start(struct I2c *i2c, uint16_t slave_addr)
+{
+       if (i2c->flags & I2C_START_R)
+               slave_addr |= I2C_READBIT;
+       else
+               slave_addr &= ~I2C_READBIT;
+
+       /*
+        * Loop on the select write sequence: when the device is busy
+        * writing previously sent data it will reply to the SLA_W
+        * control byte with a NACK.  In this case, we must
+        * keep trying until the deveice responds with an ACK.
+        */
+       ticks_t start = timer_clock();
+       while (i2c_bitbang_start())
+       {
+               if (i2c_bitbang_put(slave_addr))
+                       return;
+               else if (timer_clock() - start > ms_to_ticks(CONFIG_I2C_START_TIMEOUT))
+               {
+                       LOG_ERR("Timeout on I2C start\n");
+                       i2c->errors |= I2C_START_TIMEOUT;
+                       i2c_bitbang_stop(i2c);
+                       return;
+               }
+       }
+
+       LOG_ERR("START arbitration lost\n");
+       i2c->errors |= I2C_ARB_LOST;
+       i2c_bitbang_stop(i2c);
+       return;
+}
+
+uint8_t i2c_bitbang_get(struct I2c *i2c)
+{
+       uint8_t data = 0;
+       for (uint8_t i = 0x80; i != 0; i >>= 1)
+       {
+               SCL_LO;
+               I2C_HALFBIT_DELAY();
+               SCL_HI;
+               if (SDA_IN)
+                       data |= i;
+               else
+                       data &= ~i;
+
+               I2C_HALFBIT_DELAY();
+       }
+       SCL_LO;
+
+       /* Generate ACK/NACK */
+       if (i2c->xfer_size > 1)
+               SDA_LO;
+       else
+               SDA_HI;
+
+       I2C_HALFBIT_DELAY();
+       SCL_HI;
+       I2C_HALFBIT_DELAY();
+       SCL_LO;
+       SDA_HI;
+
+       /* Generate stop condition (if requested) */
+       if ((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP))
+               i2c_bitbang_stop(i2c);
+
+       return data;
+}
+
+void i2c_bitbang_put(struct I2c *i2c, uint8_t _data)
+{
+       /* Add ACK bit */
+       uint16_t data = (_data << 1) | 1;
+
+       for (uint16_t i = 0x100; i != 0; i >>= 1)
+       {
+               SCL_LO;
+               if (data & i)
+                       SDA_HI;
+               else
+                       SDA_LO;
+               I2C_HALFBIT_DELAY();
+
+               SCL_HI;
+               I2C_HALFBIT_DELAY();
+       }
+
+       bool ack = !SDA_IN;
+       SCL_LO;
+       I2C_HALFBIT_DELAY();
+
+       if (!ack)
+       {
+               LOG_ERR("NO ACK received\n");
+               i2c->errors |= I2C_NO_ACK;
+       }
+
+       /* Generate stop condition (if requested) */
+       if (((i2c->xfer_size == 1) && (i2c->flags & I2C_STOP)) || i2c->errors)
+               i2c_bitbang_stop(i2c);
+}