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Disable feedback current readout on flawed HW Revs #96

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sb10q merged 1 commits from atse/thermostat:disable-current-readout-pre-rev3 into master 2024-01-31 12:18:47 +08:00
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atse commented 2024-01-31 12:17:48 +08:00

Thermostats v2.2 and below have a noisy and offset feedback current tec_i caused by missing hardware on 2 MAX1968 TEC driver pins:

  1. A missing RC filter on the ITEC pin that would have isolated CPU
    sampling pulses from the signal; and
  2. Some missing buffering on the VREF pin that would have avoided
    loading the VREF signal, preventing voltage drops from the nominal 1.5V.

Since the resulting signal tec_i derived from these two signals can have an error of around +/- 100mA, and readback may affect the stability performance of the Thermostat, disable current readback entirely on affected hardware revisions for now.

See https://github.com/sinara-hw/Thermostat/issues/117 and https://github.com/sinara-hw/Thermostat/issues/120.

On hardware revisions v3.x and above, this would be fixed.

Thermostats v2.2 and below have a [noisy and offset feedback current `tec_i`](https://git.m-labs.hk/M-Labs/thermostat/issues/92) caused by missing hardware on 2 MAX1968 TEC driver pins: 1. A missing RC filter on the ITEC pin that would have isolated CPU sampling pulses from the signal; and 2. Some missing buffering on the VREF pin that would have avoided loading the VREF signal, preventing voltage drops from the nominal 1.5V. Since the resulting signal `tec_i` derived from these two signals can have an error of around +/- 100mA, and readback may affect the stability performance of the Thermostat, disable current readback entirely on affected hardware revisions for now. See https://github.com/sinara-hw/Thermostat/issues/117 and https://github.com/sinara-hw/Thermostat/issues/120. On hardware revisions v3.x and above, this would be fixed.
atse added 1 commit 2024-01-31 12:17:48 +08:00
ae3d8b51d4 Disable feedback current readout on flawed HW Revs 
Thermostats v2.2 and below have a noisy and offset feedback current
`tec_i` caused by missing hardware on 2 MAX1968 TEC driver pins:

1. A missing RC filter on the ITEC pin that would have isolated CPU
sampling pulses from the signal; and
2. Some missing buffering on the VREF pin that would have avoided
loading the VREF signal, preventing voltage drops from the nominal 1.5V.

Since the resulting signal `tec_i` derived from these two signals can
have an error of around +/- 100mA, and readback may affect the stability
performance of the Thermostat, disable current readback entirely on
affected hardware revisions for now.

See https://github.com/sinara-hw/Thermostat/issues/117 and
https://github.com/sinara-hw/Thermostat/issues/120.

On hardware revisions v3.x and above, this would be fixed.
sb10q merged commit ae3d8b51d4 into master 2024-01-31 12:18:47 +08:00
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Reference: M-Labs/thermostat#96
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