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| author | Linus Nielsen Feltzing <linus@haxx.se> | 2005-11-21 02:13:14 +0000 |
|---|---|---|
| committer | Linus Nielsen Feltzing <linus@haxx.se> | 2005-11-21 02:13:14 +0000 |
| commit | dcb8df5180658a26ea681e905586afaffe019ce9 (patch) | |
| tree | 1dab39f3068d39cbd8a57e7a35761269b8f4b75c | |
| parent | 5124844e32954cb4e8103dc29b78df6dd5d6a556 (diff) | |
| download | rockbox-dcb8df5180658a26ea681e905586afaffe019ce9.tar.gz rockbox-dcb8df5180658a26ea681e905586afaffe019ce9.zip | |
Added proper clock-stretching to the pcf50606 I2C driver
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@8018 a1c6a512-1295-4272-9138-f99709370657
| -rw-r--r-- | firmware/drivers/pcf50606.c | 38 |
1 files changed, 4 insertions, 34 deletions
diff --git a/firmware/drivers/pcf50606.c b/firmware/drivers/pcf50606.c index a2045291ec..4fe04e6171 100644 --- a/firmware/drivers/pcf50606.c +++ b/firmware/drivers/pcf50606.c @@ -38,7 +38,7 @@ #define SCL_INPUT and_l(~0x00001000, &GPIO_ENABLE) #define SCL_OUTPUT or_l( 0x00001000, &GPIO_ENABLE) #define SCL_LO and_l(~0x00001000, &GPIO_OUT) -#define SCL_HI or_l( 0x00001000, &GPIO_OUT) +#define SCL_HI SCL_INPUT;while(!SCL){};or_l(0x1000, &GPIO_OUT);SCL_OUTPUT #define SCL ( 0x00001000 & GPIO_READ) /* delay loop to achieve 400kHz at 120MHz CPU frequency */ @@ -68,28 +68,13 @@ static void pcf50606_i2c_stop(void) static void pcf50606_i2c_ack(bool ack) { - /* Here's the deal. The slave is slow, and sometimes needs to wait - before it can receive the acknowledge. Therefore it forces the clock - low until it is ready. We need to poll the clock line until it goes - high before we release the ack. - - In their infinite wisdom, iriver didn't pull up the SCL line, so - we have to drive the SCL high repeatedly to simulate a pullup. */ - SCL_LO; /* Set the clock low */ if(ack) SDA_LO; else SDA_HI; - - SCL_INPUT; /* Set the clock to input */ - while(!SCL) /* and wait for the slave to release it */ - { - SCL_OUTPUT; /* Set the clock to output */ - SCL_HI; - SCL_INPUT; /* Set the clock to input */ - DELAY; - } + + SCL_HI; DELAY; SCL_OUTPUT; @@ -100,23 +85,8 @@ static int pcf50606_i2c_getack(void) { int ret = 1; - /* Here's the deal. The slave is slow, and sometimes needs to wait - before it can send the acknowledge. Therefore it forces the clock - low until it is ready. We need to poll the clock line until it goes - high before we read the ack. - - In their infinite wisdom, iriver didn't pull up the SCL line, so - we have to drive the SCL high repeatedly to simulate a pullup. */ - SDA_INPUT; /* And set to input */ - SCL_INPUT; /* Set the clock to input */ - while(!SCL) /* and wait for the slave to release it */ - { - SCL_OUTPUT; /* Set the clock to output */ - SCL_HI; - SCL_INPUT; /* Set the clock to input */ - DELAY; - } + SCL_HI; if (SDA) /* ack failed */ |