From: Oleg Kostyuk <cub.uanic@gmail.com>
Date: Sun, 8 Sep 2013 23:54:24 +0000 (+0300)
Subject: Change I2C clock speed to 444 kHz
X-Git-Url: https://git.friedersdorff.com/?a=commitdiff_plain;h=260d7b7707bd46c54964779a76d45a87af28ffdc;p=max%2Ftmk_keyboard.git

Change I2C clock speed to 444 kHz
---

diff --git a/keyboard/ergodox/twimaster.c b/keyboard/ergodox/twimaster.c
index 6959d81c..f91c08e6 100644
--- a/keyboard/ergodox/twimaster.c
+++ b/keyboard/ergodox/twimaster.c
@@ -26,10 +26,16 @@
 *************************************************************************/
 void i2c_init(void)
 {
-  /* initialize TWI clock: 400 kHz clock, TWPS = 0 => prescaler = 1 */
+  /* initialize TWI clock
+   * minimal values in Bit Rate Register (TWBR) and minimal Prescaler
+   * bits in the TWI Status Register should give us maximal possible
+   * I2C bus speed - about 444 kHz
+   *
+   * for more details, see 20.5.2 in ATmega16/32 secification
+   */
   
-  TWSR = 0;                         /* no prescaler */
-  TWBR = ((F_CPU/SCL_CLOCK)-16)/2;  /* must be > 10 for stable operation */
+  TWSR = 0;     /* no prescaler */
+  TWBR = 10;    /* must be >= 10 for stable operation */
 
 }/* i2c_init */