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Issue2524 allow clocks below 100KHz #6934

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merged 11 commits into from
Dec 28, 2019
Merged

Issue2524 allow clocks below 100KHz #6934

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1f782bd
change bus clock (busywait) to be programmable [issue 2524], remove u…
Tech-TX Dec 21, 2019
a931e1d
change bus clock (busywait) to be programmable [issue 2524], remove u…
Tech-TX Dec 21, 2019
0d2b130
change bus clock (busywait) to be programmable [issue 2524], remove u…
Tech-TX Dec 22, 2019
3923b10
Merge branch 'master' into issue2524
Tech-TX Dec 22, 2019
387ca51
correct for underflow < 233Hz
Tech-TX Dec 22, 2019
b22de4d
change bus clock (busywait) to be programmable [issue 2524], convert …
Tech-TX Dec 23, 2019
14aed48
Merge branch 'master' into issue2524
Tech-TX Dec 24, 2019
9cf1095
updated minimum I2C speed for calculated bus clock
Tech-TX Dec 28, 2019
505b813
Merge branch 'issue2524' of https://github.com/Tech-TX/Arduino into i…
Tech-TX Dec 28, 2019
2d90dce
Merge branch 'master' into issue2524
Tech-TX Dec 28, 2019
2fa7998
Merge branch 'master' into issue2524
Tech-TX Dec 28, 2019
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109 changes: 24 additions & 85 deletions cores/esp8266/core_esp8266_si2c.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -63,7 +63,7 @@ class Twi
{
private:
unsigned int preferred_si2c_clock = 100000;
unsigned char twi_dcount = 18;
uint32_t twi_dcount = 18;
unsigned char twi_sda = 0;
unsigned char twi_scl = 0;
unsigned char twi_addr = 0;
Expand Down Expand Up @@ -112,7 +112,7 @@ class Twi
bool _slaveEnabled = false;

// Internal use functions
void ICACHE_RAM_ATTR busywait(unsigned char v);
void ICACHE_RAM_ATTR busywait(unsigned int v);
bool write_start(void);
bool write_stop(void);
bool write_bit(bool bit);
Expand Down Expand Up @@ -148,7 +148,6 @@ class Twi
void attachSlaveRxEvent(void (*function)(uint8_t*, size_t));
void attachSlaveTxEvent(void (*function)(void));
void ICACHE_RAM_ATTR reply(uint8_t ack);
void ICACHE_RAM_ATTR stop(void);
void ICACHE_RAM_ATTR releaseBus(void);
void enableSlave();
};
Expand All @@ -161,65 +160,22 @@ static Twi twi;

void Twi::setClock(unsigned int freq)
{
preferred_si2c_clock = freq;
preferred_si2c_clock = freq;

#if F_CPU == FCPU80
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
}

if (freq > 400000)
freq = 400000;
twi_dcount = (500000000 / freq); // half-cycle period in ns
twi_dcount = (1000*(twi_dcount - 1120)) / 62500; // (half cycle - overhead) / busywait loop time

#else
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
}
else if (freq <= 500000)
{
twi_dcount = 3; //about 500KHz
}
else if (freq <= 600000)
{
twi_dcount = 2; //about 600KHz
}
else
{
twi_dcount = 1; //about 700KHz
}

if (freq > 800000)
freq = 800000;
twi_dcount = (500000000 / freq); // half-cycle period in ns
twi_dcount = (1000*(twi_dcount - 560)) / 31250; // (half cycle - overhead) / busywait loop time

#endif
}

Expand Down Expand Up @@ -262,18 +218,18 @@ void Twi::enableSlave()
}
}

void ICACHE_RAM_ATTR Twi::busywait(unsigned char v)
void ICACHE_RAM_ATTR Twi::busywait(unsigned int v)
{
unsigned int i;
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-but-set-variable"
unsigned int reg;
for (i = 0; i < v; i++)
for (i = 0; i < v; i++) // loop time is 5 machine cycles: 31.25ns @ 160MHz, 62.5ns @ 80MHz
{
reg = GPI;
asm("nop"); // minimum element to keep GCC from optimizing this function out.
}
(void)reg;
#pragma GCC diagnostic pop

// {
// esp8266::polledTimeout::oneShotFastNs timeout(v);
// while(!timeout) { //
// }
}

bool Twi::write_start(void)
Expand Down Expand Up @@ -529,17 +485,6 @@ void ICACHE_RAM_ATTR Twi::reply(uint8_t ack)
}
}

void ICACHE_RAM_ATTR Twi::stop(void)
{
// send stop condition
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT) | _BV(TWSTO);
SCL_HIGH(twi.twi_scl); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
busywait(5); // Maybe this should be here
SDA_HIGH(twi.twi_sda); // _BV(TWSTO)
// update twi state
twi_state = TWI_READY;
}

void ICACHE_RAM_ATTR Twi::releaseBus(void)
{
Expand Down Expand Up @@ -657,7 +602,6 @@ void ICACHE_RAM_ATTR Twi::onTwipEvent(uint8_t status)
break;
case TW_BUS_ERROR: // bus error, illegal stop/start
twi_error = TW_BUS_ERROR;
stop();
break;
}
}
Expand Down Expand Up @@ -1018,11 +962,6 @@ extern "C" {
return twi.setAddress(a);
}

void twi_stop(void)
{
twi.stop();
}

void twi_setClock(unsigned int freq)
{
twi.setClock(freq);
Expand Down