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| author | utzig <utzig@35acf78f-673a-0410-8e92-d51de3d6d3f4> | 2014-11-13 22:58:39 +0000 |
|---|---|---|
| committer | utzig <utzig@35acf78f-673a-0410-8e92-d51de3d6d3f4> | 2014-11-13 22:58:39 +0000 |
| commit | 79a15865134fdc2522db29995bd5417e7b00a0d6 (patch) | |
| tree | 98014b44445dfcfc4cbc22f0d10ec8f11525c1e8 | |
| parent | fede49a90595738967da2199a269c8c374047ddc (diff) | |
| download | ChibiOS-79a15865134fdc2522db29995bd5417e7b00a0d6.tar.gz ChibiOS-79a15865134fdc2522db29995bd5417e7b00a0d6.tar.bz2 ChibiOS-79a15865134fdc2522db29995bd5417e7b00a0d6.zip | |
[KINETIS] Fixed I2C frequency calculation
git-svn-id: svn://svn.code.sf.net/p/chibios/svn/trunk@7504 35acf78f-673a-0410-8e92-d51de3d6d3f4
| -rw-r--r-- | os/hal/ports/KINETIS/LLD/i2c_lld.c | 46 |
1 files changed, 44 insertions, 2 deletions
diff --git a/os/hal/ports/KINETIS/LLD/i2c_lld.c b/os/hal/ports/KINETIS/LLD/i2c_lld.c index 31360dff6..0e768c0a2 100644 --- a/os/hal/ports/KINETIS/LLD/i2c_lld.c +++ b/os/hal/ports/KINETIS/LLD/i2c_lld.c @@ -58,8 +58,50 @@ I2CDriver I2CD2; /*===========================================================================*/
void config_frequency(I2CDriver *i2cp) {
- /* TODO */
- i2cp->i2c->F = 0x20;
+
+ /* Each index in the table corresponds to a a frequency
+ * divider used to generate the SCL clock from the main
+ * system clock.
+ */
+ uint16_t icr_table[] = {
+ /* 0x00 - 0x0F */
+ 20,22,24,26,28,30,34,40,28,32,36,40,44,48,56,68,
+ /* 0x10 - 0x1F */
+ 48,56,64,72,80,88,104,128,80,96,112,128,144,160,192,240,
+ /* 0x20 - 0x2F */
+ 160,192,224,256,288,320,384,480,320,384,448,512,576,640,768,960,
+ /* 0x30 - 0x3F */
+ 640,768,896,1024,1152,1280,1536,1920,1280,1536,1792,2048,2304,2560,3072,3840,
+ };
+
+ int length = sizeof(icr_table) / sizeof(icr_table[0]);
+ uint16_t divisor;
+ uint8_t i = 0, index = 0;
+ uint16_t best, diff;
+
+ if (i2cp->config != NULL)
+ divisor = KINETIS_SYSCLK_FREQUENCY / i2cp->config->clock;
+ else
+ divisor = KINETIS_SYSCLK_FREQUENCY / 100000;
+
+ best = ~0;
+ index = 0;
+ /* Tries to find the SCL clock which is the closest
+ * approximation to the clock passed in config. To
+ * stay on the safe side, only values that generate
+ * lower frequency are used.
+ */
+ for (i = 0; i < length; i++) {
+ if (icr_table[i] >= divisor) {
+ diff = icr_table[i] - divisor;
+ if (diff < best) {
+ best = diff;
+ index = i;
+ }
+ }
+ }
+
+ i2cp->i2c->F = index;
}
/**
|