diff options
Diffstat (limited to 'src/storage.cc')
| -rw-r--r-- | src/storage.cc | 32 |
1 files changed, 23 insertions, 9 deletions
diff --git a/src/storage.cc b/src/storage.cc index 2b3ea7c..6a85e22 100644 --- a/src/storage.cc +++ b/src/storage.cc @@ -139,6 +139,11 @@ uint8_t Storage::i2c_receive(uint8_t len, uint8_t *data) } while (!(TWCR & _BV(TWINT))); data[pos] = TWDR; + /* + * No error handling here -- We send the acks, the EEPROM only + * supplies raw data, so there's no way of knowing whether it's still + * talking to us or we're just reading garbage. + */ } return pos; @@ -146,7 +151,7 @@ uint8_t Storage::i2c_receive(uint8_t len, uint8_t *data) /* * Writes len bytes of data into the EEPROM, starting at byte number pos. - * Does not check for page boundaries yet. + * Does not check for page boundaries. * Includes a complete I2C transaction. */ uint8_t Storage::i2c_write(uint8_t addrhi, uint8_t addrlo, uint8_t len, uint8_t *data) @@ -157,18 +162,24 @@ uint8_t Storage::i2c_write(uint8_t addrhi, uint8_t addrlo, uint8_t len, uint8_t addr_buf[0] = addrhi; addr_buf[1] = addrlo; + /* + * The EEPROM might be busy processing a write command, which can + * take up to 10ms. Wait up to 16ms to respond before giving up. + * All other error conditions (even though they should never happen[tm]) + * are handled the same way. + */ for (num_tries = 0; num_tries < 16; num_tries++) { if (num_tries > 0) _delay_ms(1); if (i2c_start_write() != I2C_OK) - continue; + continue; // EEPROM is busy writing if (i2c_send(2, addr_buf) != 2) - continue; + continue; // should not happen if (i2c_send(len, data) != len) - continue; + continue; // should not happen i2c_stop(); return I2C_OK; @@ -180,7 +191,7 @@ uint8_t Storage::i2c_write(uint8_t addrhi, uint8_t addrlo, uint8_t len, uint8_t /* * Reads len bytes of data from the EEPROM, starting at byte number pos. - * Does not check for page boundaries yet. + * Does not check for page boundaries. * Includes a complete I2C transaction. */ uint8_t Storage::i2c_read(uint8_t addrhi, uint8_t addrlo, uint8_t len, uint8_t *data) @@ -191,21 +202,24 @@ uint8_t Storage::i2c_read(uint8_t addrhi, uint8_t addrlo, uint8_t len, uint8_t * addr_buf[0] = addrhi; addr_buf[1] = addrlo; + /* + * See comments in i2c_write. + */ for (num_tries = 0; num_tries < 16; num_tries++) { if (num_tries > 0) _delay_ms(1); if (i2c_start_write() != I2C_OK) - continue; + continue; // EEPROM is busy writing if (i2c_send(2, addr_buf) != 2) - continue; + continue; // should not happen if (i2c_start_read() != I2C_OK) - continue; + continue; // should not happen if (i2c_receive(len, data) != len) - continue; + continue; // should not happen i2c_stop(); return I2C_OK; |