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authorDaniel Friesel <derf@finalrewind.org>2018-07-14 14:42:00 +0200
committerDaniel Friesel <derf@finalrewind.org>2018-07-14 14:42:00 +0200
commit8b71c58ab33c788bb958f04e46ea248c72eddc42 (patch)
tree9034157621b0f53d8c65bb5d255bc25ca8a98524 /src
parentb2f7f066dbeed346e6d70414593cad2d918c2bd4 (diff)
arduino-nano: i2c: Use idle waiting
Diffstat (limited to 'src')
-rw-r--r--src/arch/arduino-nano/driver/i2c.cc39
1 files changed, 21 insertions, 18 deletions
diff --git a/src/arch/arduino-nano/driver/i2c.cc b/src/arch/arduino-nano/driver/i2c.cc
index a644ca9..cfbea59 100644
--- a/src/arch/arduino-nano/driver/i2c.cc
+++ b/src/arch/arduino-nano/driver/i2c.cc
@@ -1,5 +1,15 @@
#include "driver/i2c.h"
+#include "arch.h"
#include <avr/io.h>
+#include <avr/interrupt.h>
+
+inline void await_twint(unsigned char twcr_values)
+{
+ TWCR = twcr_values | _BV(TWINT) | _BV(TWIE);
+ while (!(TWCR & _BV(TWINT))) {
+ arch.idle();
+ }
+}
/*
* Send an I2C (re)start condition and the EEPROM address in read mode. Returns
@@ -7,16 +17,14 @@
*/
static signed char i2c_start_read(unsigned char addr)
{
- TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
- while (!(TWCR & _BV(TWINT)));
+ await_twint(_BV(TWSTA) | _BV(TWEN));
if (!(TWSR & 0x18)) // 0x08 == START ok, 0x10 == RESTART ok
return -1;
// Note: The R byte ("... | 1") causes the TWI momodule to switch to
// Master Receive mode
TWDR = (addr << 1) | 1;
- TWCR = _BV(TWINT) | _BV(TWEN);
- while (!(TWCR & _BV(TWINT)));
+ await_twint(_BV(TWEN));
if (TWSR != 0x40) // 0x40 == SLA+R transmitted, ACK receveid
return -2;
@@ -29,14 +37,12 @@ static signed char i2c_start_read(unsigned char addr)
*/
static signed char i2c_start_write(unsigned char addr)
{
- TWCR = _BV(TWINT) | _BV(TWSTA) | _BV(TWEN);
- while (!(TWCR & _BV(TWINT)));
+ await_twint(_BV(TWSTA) | _BV(TWEN));
if (!(TWSR & 0x18)) // 0x08 == START ok, 0x10 == RESTART ok
return -1;
TWDR = (addr<< 1) | 0;
- TWCR = _BV(TWINT) | _BV(TWEN);
- while (!(TWCR & _BV(TWINT)));
+ await_twint(_BV(TWEN));
if (TWSR != 0x18) // 0x18 == SLA+W transmitted, ACK received
return -2;
@@ -61,8 +67,7 @@ static signed char i2c_send(uint8_t len, uint8_t *data)
for (pos = 0; pos < len; pos++) {
TWDR = data[pos];
- TWCR = _BV(TWINT) | _BV(TWEN);
- while (!(TWCR & _BV(TWINT)));
+ await_twint(_BV(TWEN));
if (TWSR != 0x28) // 0x28 == byte transmitted, ACK received
return pos;
}
@@ -79,14 +84,7 @@ static signed char i2c_receive(uint8_t len, uint8_t *data)
uint8_t pos = 0;
for (pos = 0; pos < len; pos++) {
- if (pos == len-1) {
- // Don't ACK the last byte
- TWCR = _BV(TWINT) | _BV(TWEN);
- } else {
- // Automatically send ACK
- TWCR = _BV(TWINT) | _BV(TWEN) | _BV(TWEA);
- }
- while (!(TWCR & _BV(TWINT)));
+ await_twint(_BV(TWEN) | ( _BV(TWEA) * (pos < len-1) ) );
data[pos] = TWDR;
/*
* No error handling here -- We send the acks, the EEPROM only
@@ -111,6 +109,7 @@ void I2C::scan(unsigned int *results)
for (unsigned char address = 0; address < 128; address++) {
if (i2c_start_read(address) == 0) {
results[address / (8 * sizeof(unsigned int))] |= 1 << (address % (8 * sizeof(unsigned int)));
+ i2c_stop();
}
}
i2c_stop();
@@ -144,3 +143,7 @@ signed char I2C::xmit(unsigned char address,
}
I2C i2c;
+
+ISR(TWI_vect)
+{
+}