8000 Issue2524 allow clocks below 100KHz by Tech-TX · Pull Request #6934 · esp8266/Arduino · GitHub
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Issue2524 allow clocks below 100KHz #6934

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Merged
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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change bus clock (busywait) to be programmable [issue 2524], convert … 
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@Tech-TX
Tech-TX committed Dec 23, 2019
commit b22de4dae9647b5cb1c52382d82cac77173bd91f
54 changes: 27 additions & 27 deletions cores/esp8266/core_esp8266_si2c.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,8 @@ extern "C" {
{
GPEC = (1 << twi_sda);
}
static inline __attribute__((always_inline)) bool SDA_READ(const int twi_sda)
{
static inline __attribute__((always_inline)) bool SDA_READ(const int twi_sda)
{
return (GPI & (1 << twi_sda)) != 0;
}
static inline __attribute__((always_inline)) void SCL_LOW(const int twi_scl)
Expand All @@ -52,8 +52,8 @@ extern "C" {
{
GPEC = (1 << twi_scl);
}
static inline __attribute__((always_inline)) bool SCL_READ(const int twi_scl)
{
static inline __attribute__((always_inline)) bool SCL_READ(const int twi_scl)
{
return (GPI & (1 << twi_scl)) != 0;
}

Expand Down Expand Up @@ -160,22 +160,22 @@ static Twi twi;

void Twi::setClock(unsigned int freq)
{
if (freq < 250) // minimum freq 250Hz to prevent overflow @ 232Hz
freq = 250;
preferred_si2c_clock = freq;
if (freq < 250) // minimum freq 250Hz to prevent overflow @ 232Hz
freq = 250;
preferred_si2c_clock = freq;

#if F_CPU == FCPU80

if (freq > 400000)
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 > 800000)
freq = 800000;
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

Expand Down Expand Up @@ -226,7 +226,7 @@ void Twi::enableSlave()
unsigned int i;
for (i = 0; i < v; i++) // loop time is 5 machine cycles: 31.25ns @ 160MHz, 62.5ns @ 80MHz
{
asm("nop"); // minimum element to keep GCC from optimizing this function out.
asm("nop"); // minimum element to keep GCC from optimizing this function out.
}
}

Expand Down Expand Up @@ -472,14 +472,14 @@ void ICACHE_RAM_ATTR Twi::reply(uint8_t ack)
if (ack)
{
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT) | _BV(TWEA);
SCL_HIGH(twi.twi_scl); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
SCL_HIGH(twi.twi_scl); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
}
else
{
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWINT);
SCL_HIGH(twi.twi_scl); // _BV(TWINT)
twi_ack = 0; // ~_BV(TWEA)
SCL_HIGH(twi.twi_scl); // _BV(TWINT)
twi_ack = 0; // ~_BV(TWEA)
}
}

Expand All @@ -488,8 +488,8 @@ void ICACHE_RAM_ATTR Twi::releaseBus(void)
{
// release bus
//TWCR = _BV(TWEN) | _BV(TWIE) | _BV(TWEA) | _BV(TWINT);
SCL_HIGH(twi.twi_scl); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
SCL_HIGH(twi.twi_scl); // _BV(TWINT)
twi_ack = 1; // _BV(TWEA)
SDA_HIGH(twi.twi_sda);

// update twi state
Expand Down Expand Up @@ -660,11 +660,11 @@ void ICACHE_RAM_ATTR Twi::onSclChange(void)
unsigned int scl;

// Store bool return in int to reduce final code size.
sda = SDA_READ(twi.twi_sda);
scl = SCL_READ(twi.twi_scl);

twi.twip_status = 0xF8; // reset TWI status
twi.twip_status = 0xF8; // reset TWI status

int twip_state_mask = S2M(twi.twip_state);
IFSTATE(S2M(TWIP_START) | S2M(TWIP_REP_START) | S2M(TWIP_SLA_W) | S2M(TWIP_READ))
Expand Down Expand Up @@ -739,7 +739,7 @@ void ICACHE_RAM_ATTR Twi::onSclChange(void)
}
else
{
SCL_LOW(twi.twi_scl); // clock stretching
SCL_LOW(twi.twi_scl); // clock stretching
SDA_HIGH(twi.twi_sda);
twi.twip_mode = TWIPM_ADDRESSED;
if (!(twi.twi_data & 0x01))
Expand All @@ -757,7 +757,7 @@ void ICACHE_RAM_ATTR Twi::onSclChange(void)
}
else
{
SCL_LOW(twi.twi_scl); // clock stretching
SCL_LOW(twi.twi_scl); // clock stretching
SDA_HIGH(twi.twi_sda);
if (!twi.twi_ack)
{
Expand Down Expand Up @@ -835,7 +835,7 @@ void ICACHE_RAM_ATTR Twi::onSclChange(void)
}
else
{
SCL_LOW(twi.twi_scl); // clock stretching
SCL_LOW(twi.twi_scl); // clock stretching
if (twi.twi_ack && twi.twi_ack_rec)
{
twi.onTwipEvent(TW_ST_DATA_ACK);
Expand Down Expand Up @@ -881,7 +881,7 @@ void ICACHE_RAM_ATTR Twi::onSdaChange(void)
else IFSTATE(S2M(TWIP_START) | S2M(TWIP_REP_START) | S2M(TWIP_SEND_ACK) | S2M(TWIP_WAIT_ACK) | S2M(TWIP_SLA_R) | S2M(TWIP_REC_ACK) | S2M(TWIP_READ_ACK) | S2M(TWIP_RWAIT_ACK) | S2M(TWIP_WRITE))
{
// START or STOP
SDA_HIGH(twi.twi_sda); // Should not be necessary
SDA_HIGH(twi.twi_sda); // Should not be necessary
twi.onTwipEvent(TW_BUS_ERROR);
twi.twip_mode = TWIPM_WAIT;
twi.twip_state = TWIP_BUS_ERR;
Expand All @@ -891,7 +891,7 @@ void ICACHE_RAM_ATTR Twi::onSdaChange(void)
if (sda)
{
// STOP
SCL_LOW(twi.twi_scl); // clock stretching
SCL_LOW(twi.twi_scl); // generates a low SCL pulse after STOP
ets_timer_disarm(&twi.timer);
twi.twip_state = TWIP_IDLE;
twi.twip_mode = TWIPM_IDLE;
Expand Down Expand Up @@ -925,7 +925,7 @@ void ICACHE_RAM_ATTR Twi::onSdaChange(void)
else
{
// during first bit in byte transfer - ok
SCL_LOW(twi.twi_scl); // clock stretching
SCL_LOW(twi.twi_scl); // clock stretching
twi.onTwipEvent(TW_SR_STOP);
if (sda)
{
Expand Down
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