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stm32:i2c-v2: Clarify digital filter setting 

Drop redundant field definitions, fix truncation of argument bug and add
documentation.

Fixes: https://github.com/libopencm3/libopencm3/issues/831
This commit is contained in:
Karl Palsson 2017-10-26 21:54:30 +00:00 committed by Karl Palsson
parent 965d28ecbe
commit ed90df85f0
2 changed files with 13 additions and 19 deletions
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21
include/libopencm3/stm32/common/i2c_common_v2.h
View File

@ -137,24 +137,9 @@ specific memorymap.h header before including this header file.*/
/* ANFOFF: Analog noise filter OFF */
#define I2C_CR1_ANFOFF (1 << 12)
/* DNF[3:0]: Digital noise filter */
#define I2C_CR1_DNF_DISABLED (0x0 << 8)
#define I2C_CR1_DNF_UP_1_TI2CCLK (0x1 << 8)
#define I2C_CR1_DNF_UP_2_TI2CCLK (0x2 << 8)
#define I2C_CR1_DNF_UP_3_TI2CCLK (0x3 << 8)
#define I2C_CR1_DNF_UP_4_TI2CCLK (0x4 << 8)
#define I2C_CR1_DNF_UP_5_TI2CCLK (0x5 << 8)
#define I2C_CR1_DNF_UP_6_TI2CCLK (0x6 << 8)
#define I2C_CR1_DNF_UP_7_TI2CCLK (0x7 << 8)
#define I2C_CR1_DNF_UP_8_TI2CCLK (0x8 << 8)
#define I2C_CR1_DNF_UP_9_TI2CCLK (0x9 << 8)
#define I2C_CR1_DNF_UP_10_TI2CCLK (0xA << 8)
#define I2C_CR1_DNF_UP_11_TI2CCLK (0xB << 8)
#define I2C_CR1_DNF_UP_12_TI2CCLK (0xC << 8)
#define I2C_CR1_DNF_UP_13_TI2CCLK (0xD << 8)
#define I2C_CR1_DNF_UP_14_TI2CCLK (0xE << 8)
#define I2C_CR1_DNF_UP_15_TI2CCLK (0xF << 8)
#define I2C_CR1_DNF_MASK (0xF << 8)
/** DNF[3:0]: Digital noise filter. */
#define I2C_CR1_DNF_MASK 0xF
#define I2C_CR1_DNF_SHIFT 8
/* ERRIE: Error interrupts enable */
#define I2C_CR1_ERRIE (1 << 7)

11
lib/stm32/common/i2c_common_v2.c
View File

@ -188,9 +188,18 @@ void i2c_disable_analog_filter(uint32_t i2c)
I2C_CR1(i2c) |= I2C_CR1_ANFOFF;
}
/**
* Set the I2C digital filter.
* These bits are used to configure the digital noise filter on SDA and
* SCL input. The digital filter will filter spikes with a length of up
* to dnf_setting * I2CCLK clocks
* @param i2c peripheral of interest
* @param dnf_setting 0 to disable, else 1..15 i2c clocks
*/
void i2c_set_digital_filter(uint32_t i2c, uint8_t dnf_setting)
{
I2C_CR1(i2c) = (I2C_CR1(i2c) & ~I2C_CR1_DNF_MASK) | dnf_setting;
I2C_CR1(i2c) = (I2C_CR1(i2c) & ~(I2C_CR1_DNF_MASK << I2C_CR1_DNF_SHIFT)) |
(dnf_setting << I2C_CR1_DNF_SHIFT);
}
/* t_presc= (presc+1)*t_i2cclk */