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firmware: switch the DAC off too when switching off Vio #243

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merged 1 commit into from
Feb 7, 2023
Merged

firmware: switch the DAC off too when switching off Vio #243

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32 changes: 18 additions & 14 deletions firmware/dac_ldo.c
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Original file line number Diff line number Diff line change
Expand Up @@ -60,21 +60,23 @@ bool iobuf_set_voltage(uint8_t mask, __xdata const uint16_t *millivolts_ptr) {
if((mask & IO_BUF_A) && millivolts > glasgow_config.voltage_limit[0]) return false;
if((mask & IO_BUF_B) && millivolts > glasgow_config.voltage_limit[1]) return false;

// Just disable the LDOs, DAC power is irrelevant
if(millivolts == 0) {
// disable the LDOs before any I2C comms, we may need to be fast in case of an alert
IOD &= ~pin_mask;
return true;
}

// Compute the DAC code word
if(millivolts < MIN_VOLTAGE || millivolts > MAX_VOLTAGE)
return false;

// Offset 1650, slope -15.2, 0x1000/15.2 = 269
// The DAC has a 12-bit code word, so we only shift back by 8
code_word = (254 << 4) - ((((millivolts - 1650) >> 4) * 269) >> 4);
code_bytes[0] = code_word >> 8;
code_bytes[1] = code_word & 0xff;
code_bytes[0] = 0;
code_bytes[1] = 0;
} else {
// Compute the DAC code word
if(millivolts < MIN_VOLTAGE || millivolts > MAX_VOLTAGE)
return false;

// Offset 1650, slope -15.2, 0x1000/15.2 = 269
// The DAC has a 12-bit code word, so we only shift back by 8
code_word = (254 << 4) - ((((millivolts - 1650) >> 4) * 269) >> 4);
code_bytes[0] = code_word >> 8;
code_bytes[1] = code_word & 0xff;
}

// Send the DAC code word
if(!dac_start(mask, /*read=*/false))
Expand All @@ -86,8 +88,10 @@ bool iobuf_set_voltage(uint8_t mask, __xdata const uint16_t *millivolts_ptr) {
if(!i2c_stop())
return false;

// Enable LDO(s)
IOD |= pin_mask;
if(millivolts != 0) {
// Enable LDO(s)
IOD |= pin_mask;
}

return true;
}
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