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LPC MCUXpresso: Remove extra I2C transaction on byte write #11003

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Merged
merged 1 commit into from
Jul 15, 2019
Merged

LPC MCUXpresso: Remove extra I2C transaction on byte write #11003

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37 changes: 18 additions & 19 deletions targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC/i2c_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@ void i2c_init(i2c_t *obj, PinName sda, PinName scl)
uint32_t i2c_scl = pinmap_peripheral(scl, PinMap_I2C_SCL);
obj->instance = pinmap_merge(i2c_sda, i2c_scl);
obj->next_repeated_start = 0;
obj->issue_start = 0;
MBED_ASSERT((int)obj->instance != NC);

i2c_master_config_t master_config;
Expand Down Expand Up @@ -92,23 +93,7 @@ void i2c_init(i2c_t *obj, PinName sda, PinName scl)

int i2c_start(i2c_t *obj)
{
I2C_Type *base = i2c_addrs[obj->instance];
uint32_t status;

do {
status = I2C_GetStatusFlags(base);
} while ((status & I2C_STAT_MSTPENDING_MASK) == 0);

/* Clear controller state. */
I2C_MasterClearStatusFlags(base, I2C_STAT_MSTARBLOSS_MASK | I2C_STAT_MSTSTSTPERR_MASK);

/* Start the transfer */
base->MSTDAT = 0;
base->MSTCTL = I2C_MSTCTL_MSTSTART_MASK;

do {
status = I2C_GetStatusFlags(base);
} while ((status & I2C_STAT_MSTPENDING_MASK) == 0);
obj->issue_start = 1;

return 0;
}
Expand All @@ -131,6 +116,8 @@ int i2c_stop(i2c_t *obj)
status = I2C_GetStatusFlags(base);
} while ((status & I2C_STAT_MSTPENDING_MASK) == 0);

obj->issue_start = 0;

return 0;
}

Expand Down Expand Up @@ -236,12 +223,24 @@ int i2c_byte_write(i2c_t *obj, int data)
// write the data
base->MSTDAT = data;

base->MSTCTL = I2C_MSTCTL_MSTCONTINUE_MASK;

do {
status = I2C_GetStatusFlags(base);
} while ((status & I2C_STAT_MSTPENDING_MASK) == 0);

/* Clear controller state. */
I2C_MasterClearStatusFlags(base, I2C_STAT_MSTARBLOSS_MASK | I2C_STAT_MSTSTSTPERR_MASK);

if (obj->issue_start) {
base->MSTCTL = I2C_MSTCTL_MSTSTART_MASK;
/* Clear the flag */
obj->issue_start = 0;
} else {
base->MSTCTL = I2C_MSTCTL_MSTCONTINUE_MASK;
}

do {
status = I2C_GetStatusFlags(base);
} while ((status & I2C_STAT_MSTPENDING_MASK) == 0);

/* Check if arbitration lost */
if (status & I2C_STAT_MSTARBLOSS_MASK) {
Expand Down
1 change: 1 addition & 0 deletions targets/TARGET_NXP/TARGET_MCUXpresso_MCUS/TARGET_LPC/objects.h
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,7 @@ struct analogin_s {
struct i2c_s {
uint32_t instance;
uint8_t next_repeated_start;
uint8_t issue_start;
};

struct spi_s {
Expand Down