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ADC saturation

The controller monitors its analog inputs for saturation. An input is saturated when its voltage at the digital signal processor (DSP), after the input voltage divider, is above 3.3 V for 100 PWM periods. A saturated input cannot be measured correctly, and a voltage above the input rating can also damage the controller. You can choose, for each input, whether saturation triggers a fault or a warning.

Firmware

Choosing fault or warning per input is available in firmware 6.026 and later.

Prerequisites

Prerequisites

  • All inputs are wired, and each input voltage is within its rating.

How it works

Behaviour depends on the firmware version:

  • 6.026 and later: for each input, the matching bit of ADC Saturation Control decides the response. With the bit cleared (0), saturation triggers Analog Input Voltage Range (Faults3 bit 2), which disables the motor phase bridge. With the bit set (1), saturation sets ADC saturation warning (Warnings2 bit 9) instead.
  • 6.025 rev02: saturation of any input sets the ADC saturation warning. The fault never triggers.
  • 6.024 to 6.025: saturation of any input triggers the fault.

ADC Saturation Event Source shows which inputs have saturated, using the same bit order.

Bit Input
0 Phase A current
1 Phase C current
2 Phase B voltage
3 Phase A voltage
4 Phase C voltage
5 Brake 2
6 Internal rail monitor (12 V or 5 V)
7 Light supply
8 BMS
9 DC battery voltage
10 Brake 1
11 Throttle
12 Heat sink temperature
13 Internal DSP temperature
14 to 15 Reserved

Bits of ADC Saturation Control and ADC Saturation Event Source

Neither the fault nor the warning can be disabled. The warning cannot be cleared until you fix the input that causes it.

Configure ADC saturation

  1. Decide which inputs should report saturation as a warning instead of a fault.
  2. Set the matching bits in ADC Saturation Control. Leave all other bits at 0.
  3. Save the parameters to flash.

WARNING

Reporting saturation as a warning lets the motor keep running while the controller cannot measure that input correctly. Only do this for inputs where an incorrect reading cannot cause unsafe operation.

Changing the response does not protect the input. A voltage above the input rating can damage the controller whether saturation is reported as a fault or a warning. Always fix the cause.

Verify

  1. Run the system through its normal range.
  2. Check that ADC Saturation Event Source shows no saturated inputs. If it does, remove the source of voltage that makes the input exceed its rating.

Parameters

Parameter Address Units Description
ADC Saturation Control 239 Bit field, one bit per input. 1: saturation triggers a warning. 0: saturation triggers a fault.
ADC Saturation Event Source 1725 Bit field, one bit per input. 1: the input has saturated.

Parameters used on this page