From: batt Date: Fri, 23 Jul 2010 19:41:23 +0000 (+0000) Subject: First version of new i2c bitbang API. X-Git-Tag: 2.6.0~288^2~31 X-Git-Url: https://codewiz.org/gitweb?a=commitdiff_plain;h=ec1f9b136d8b9ec44272ba7ab8ddc4b729589af2;p=bertos.git 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 5e9dfb0c..45847c93 100644 --- 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); +}