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Added 50kHz operation mode for I2C/Wire library #3401

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Merged
merged 2 commits into from
Mar 24, 2018
Merged

Added 50kHz operation mode for I2C/Wire library #3401

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03fee25
Added 50kHz operation mode for I2C/Wire library
derSeddy Jul 4, 2017
6e6f13c
Merge branch 'master' into patch-1
devyte Mar 24, 2018
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45 changes: 30 additions & 15 deletions cores/esp8266/core_esp8266_si2c.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,13 +45,15 @@ static uint32_t twi_clockStretchLimit;

void twi_setClock(unsigned int freq){
#if F_CPU == FCPU80
if(freq <= 100000) twi_dcount = 19;//about 100KHz
if(freq <= 50000) twi_dcount = 38;//about 50KHz
else if(freq <= 100000) twi_dcount = 19;//about 100KHz
else if(freq <= 200000) twi_dcount = 8;//about 200KHz
else if(freq <= 300000) twi_dcount = 3;//about 300KHz
else if(freq <= 400000) twi_dcount = 1;//about 400KHz
else twi_dcount = 1;//about 400KHz
#else
if(freq <= 100000) twi_dcount = 32;//about 100KHz
if(freq <= 50000) twi_dcount = 64;//about 50KHz
else if(freq <= 100000) twi_dcount = 32;//about 100KHz
else if(freq <= 200000) twi_dcount = 14;//about 200KHz
else if(freq <= 300000) twi_dcount = 8;//about 300KHz
else if(freq <= 400000) twi_dcount = 5;//about 400KHz
Expand Down Expand Up @@ -85,14 +87,16 @@ static void twi_delay(unsigned char v){
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
unsigned int reg;
for(i=0;i<v;i++) reg = GPI;
for(i=0;i<v;i++)
reg = GPI;
#pragma GCC diagnostic pop
}

static bool twi_write_start(void) {
SCL_HIGH();
SDA_HIGH();
if (SDA_READ() == 0) return false;
if (SDA_READ() == 0)
return false;
twi_delay(twi_dcount);
SDA_LOW();
twi_delay(twi_dcount);
Expand All @@ -116,8 +120,10 @@ static bool twi_write_stop(void){
static bool twi_write_bit(bool bit) {
uint32_t i = 0;
SCL_LOW();
if (bit) SDA_HIGH();
else SDA_LOW();
if (bit)
SDA_HIGH();
else
SDA_LOW();
twi_delay(twi_dcount+1);
SCL_HIGH();
while (SCL_READ() == 0 && (i++) < twi_clockStretchLimit);// Clock stretching
Expand Down Expand Up @@ -149,25 +155,30 @@ static bool twi_write_byte(unsigned char byte) {
static unsigned char twi_read_byte(bool nack) {
unsigned char byte = 0;
unsigned char bit;
for (bit = 0; bit < 8; bit++) byte = (byte << 1) | twi_read_bit();
for (bit = 0; bit < 8; bit++)
byte = (byte << 1) | twi_read_bit();
twi_write_bit(nack);
return byte;
}

unsigned char twi_writeTo(unsigned char address, unsigned char * buf, unsigned int len, unsigned char sendStop){
unsigned int i;
if(!twi_write_start()) return 4;//line busy
if(!twi_write_start())
return 4;//line busy
if(!twi_write_byte(((address << 1) | 0) & 0xFF)) {
if (sendStop) twi_write_stop();
if (sendStop)
twi_write_stop();
return 2; //received NACK on transmit of address
}
for(i=0; i<len; i++) {
if(!twi_write_byte(buf[i])) {
if (sendStop) twi_write_stop();
if (sendStop)
twi_write_stop();
return 3;//received NACK on transmit of data
}
}
if(sendStop) twi_write_stop();
if(sendStop)
twi_write_stop();
i = 0;
while(SDA_READ() == 0 && (i++) < 10){
SCL_LOW();
Expand All @@ -180,14 +191,18 @@ unsigned char twi_writeTo(unsigned char address, unsigned char * buf, unsigned i

unsigned char twi_readFrom(unsigned char address, unsigned char* buf, unsigned int len, unsigned char sendStop){
unsigned int i;
if(!twi_write_start()) return 4;//line busy
if(!twi_write_start())
return 4;//line busy
if(!twi_write_byte(((address << 1) | 1) & 0xFF)) {
if (sendStop) twi_write_stop();
if (sendStop)
twi_write_stop();
return 2;//received NACK on transmit of address
}
for(i=0; i<(len-1); i++) buf[i] = twi_read_byte(false);
for(i=0; i<(len-1); i++)
buf[i] = twi_read_byte(false);
buf[len-1] = twi_read_byte(true);
if(sendStop) twi_write_stop();
if(sendStop)
twi_write_stop();
i = 0;
while(SDA_READ() == 0 && (i++) < 10){
SCL_LOW();
Expand Down