Ignition Timers

Platforms with an ignition MCU control the vehicle power sequence with a set of timers. The timers decide how the PC powers up when you turn the key and how it powers down when you turn it off.

Two platforms have them, and their timer sets are different:

Platform	Timers	Unit
In-CarPC CQ20	Four	Always seconds
In-CarPC CQ40N series	Five	Selectable, minutes or seconds

The timers are stored in the MCU’s non-volatile memory on both platforms, so they persist across restarts and power loss. This is different from the CQ40 series digital outputs, which reset every time the machine reboots.

The CQ40 series has no ignition timers. There, pcu-cli ign reports ERROR: Ignition timers are not available on In-CarPC CQ40 series. and exits with code 2. See Supported Platforms for the feature comparison.

Older models: use CQUtils for now

pcu is new, and we are still backporting support for older In-CarPC models, including ignition management. If your machine is not yet supported, use the CQUtils program preinstalled on the desktop in the meantime. Not sure which applies to your machine? Contact In-CarPC support.

In-CarPC CQ20

The CQ20 has four timers, all counted in seconds.

How the power sequence works

The MCU watches the vehicle’s ignition signal and steps the PC through a fixed sequence at each change.

Startup. When the ignition comes on, the MCU waits the Anti-Crank Delay before doing anything. This filters out the brief, unstable signals that happen while an engine is cranking. If the ignition signal drops during this wait, the MCU cancels the boot entirely. Once the delay passes and the ignition is still on, the MCU applies DC power, waits the Boot Delay for the supply voltages to stabilise, then presses the power button to start the PC.

Shutdown. When the ignition goes off, the MCU does not shut the PC down straight away. It waits the Shutdown Delay, which gives you time to restart the engine or finish what you are doing. If the ignition comes back on within that window, the shutdown is cancelled. Once the delay expires, the MCU sends the operating system a shutdown command. If the OS has not finished shutting down after the Force Off Timeout, the MCU cuts power anyway, so a hung shutdown cannot sit there draining the vehicle battery.

The four CQ20 timers

Timer	Label	Range	Default	Recommended
ign-on-delay	Anti-Crank Delay	1-60s	6s	3-10s
sw-on-delay	Boot Delay	1-60s	4s	2-5s
sw-off-delay	Shutdown Delay	3-7200s	300s (5m)	30-300s
pw-off-delay	Force Off Timeout	10-7200s	120s (2m)	60-180s

Anti-Crank Delay (ign-on-delay)

How long the MCU waits after detecting the ignition signal before turning on DC power. This filters out the brief, unstable signals that happen when an engine is cranking, so the PC will not try to boot until the engine is properly running.

• Too low: the PC may try to boot while the engine is still cranking, then lose power mid-startup.
• Too high: the PC takes longer than necessary to start after the key is turned.

Boot Delay (sw-on-delay)

How long the MCU waits after applying DC power before pressing the power button. This gives the power supply time to stabilise, so the motherboard receives clean voltage when it starts up.

• Too low: the power button may be pressed before voltages have stabilised.
• Too high: adds unnecessary delay to the boot process.

Shutdown Delay (sw-off-delay)

How long the MCU waits after the ignition signal is removed before telling the operating system to shut down. This gives you time to restart the engine without the PC shutting down, and gives running tasks time to finish. If the ignition comes back during this window, the shutdown is cancelled.

• Too low: brief ignition interruptions could trigger unwanted shutdowns, and the OS may not have time to save data.
• Too high: the PC runs for a long time after the vehicle is turned off, draining the battery.

Force Off Timeout (pw-off-delay)

How long the MCU waits after sending the shutdown command before cutting power regardless of whether the OS has finished shutting down. This is a safety net: if the OS freezes during shutdown (a stuck update, a crashed program), the MCU cuts power to prevent the battery draining indefinitely. Under normal operation this timer should never trigger.

• Too low: the OS may not have finished shutting down, risking data loss or file corruption.
• Too high: if the OS is frozen, the PC sits draining the battery for too long.

In-CarPC CQ40N series

The CQ40N series has five timers. Three cover the ignition sequence and two cover running on the UPS battery after the vehicle supply is lost. Four of the five are counted in a delay unit you can switch between minutes and seconds; the Ignition On Delay is always in seconds.

How the power sequence works

Startup. When the ignition comes on, the MCU waits the Ignition On Delay, then starts the system. This is a shorter sequence than the CQ20’s: there is one delay between the key and the system starting, not two.

Shutdown. When the ignition goes off, the MCU waits the Ignition Off Delay, then begins the shutdown. If the shutdown has not completed after the Force Off Timeout, the MCU cuts power anyway.

Power loss and the UPS battery. The two UPS timers are separate from the ignition sequence and only have an effect when the UPS battery is fitted. If the main supply is lost, the UPS Off Delay is how long the system keeps running on the battery before shutting down. Once that shutdown starts, the UPS Force Off Timeout is the backstop that cuts power if the OS does not finish.

The five CQ40N timers

Timer	Label	Range	Default	Recommended	Unit
ign-on-delay	Ignition On Delay	0-255s	7s	3-10s	Always seconds
ign-off-delay	Ignition Off Delay	0-255	1	1-10	Follows the delay unit
pw-off-delay	Force Off Timeout	0-255	15	5-30	Follows the delay unit
ups-off-delay	UPS Off Delay	0-20	5	5-10	Follows the delay unit
ups-pw-off-delay	UPS Force Off Timeout	0-255	2	1-5	Follows the delay unit

The four timers that follow the delay unit are shown without a unit on purpose. The number stored in the MCU is a plain count, and the delay unit decides what it counts. A value of 5 means five minutes or five seconds depending on the current setting.

ups-off-delay is the only one of the five whose maximum is not 255. Its limit of 20 is enforced by the MCU itself, so a larger value is not accepted even if something tries to write it.

Ignition On Delay (ign-on-delay)

How long the MCU waits after the ignition switches on before the system powers up. This filters out the brief, unstable signals that happen while an engine is cranking. Unlike the other four, this timer is always counted in seconds, whatever the delay unit is set to.

• Too low: the PC may try to start while the engine is still cranking, then lose power mid-startup.
• Too high: the PC takes longer than necessary to start after the key is turned.

Ignition Off Delay (ign-off-delay)

How long the MCU waits after the ignition switches off before the shutdown starts. This gives you time to restart the engine or finish what you are doing.

• Too low: brief ignition interruptions could trigger unwanted shutdowns.
• Too high: the PC runs for a long time after the vehicle is turned off, draining the battery.

Force Off Timeout (pw-off-delay)

How long the MCU waits after the shutdown starts before cutting power anyway. This is a safety net for a shutdown that hangs. Under normal operation it should never trigger.

• Too low: the OS may not have finished shutting down, risking data loss or file corruption.
• Too high: if the OS is frozen, the PC sits draining the battery for too long.

UPS Off Delay (ups-off-delay)

How long the system keeps running on the UPS battery after the main supply is lost, before it starts to shut down. This only has an effect when the UPS battery is fitted. The range is 0-20.

• Too low: a brief supply interruption shuts the machine down when it did not need to.
• Too high: the UPS battery is drained further before the machine starts shutting down.

UPS Force Off Timeout (ups-pw-off-delay)

How long the MCU waits after a shutdown on UPS battery starts before cutting power anyway. This is the UPS equivalent of the Force Off Timeout, and it only has an effect when the UPS battery is fitted.

• Too low: the OS may not have finished shutting down before the battery is cut.
• Too high: the UPS battery is drained further by a shutdown that has already hung.

The delay unit

The CQ40N counts four of its five timers in a unit you can change. From the factory the unit is minutes. You can switch it to seconds, and switch back.

The unit is stored in the MCU alongside the timers, so it also survives a restart and power loss.

Changing the unit does not convert the stored values

The MCU stores those four timers as plain counts, not as durations. Switching the unit changes what the counts mean, and nothing recalculates them.

A Force Off Timeout set to 15 with the unit on minutes is a fifteen minute backstop. Switch the unit to seconds and the same stored 15 becomes a fifteen second backstop, which can cut power to the PC before the operating system has finished shutting down.

Always re-check every timer value after changing the unit.

The Ignition On Delay is not affected. That timer is always counted in seconds whatever the unit is set to.

Read the current unit with pcu-cli ign unit, and change it with pcu-cli ign unit minutes or pcu-cli ign unit seconds. Both are covered on the Command Reference. In the app, use the “Delay Unit” card on the Ignition page.

Changing a timer

Timer writes change how the vehicle powers the PC

Each write goes straight to the MCU and takes effect immediately. Setting a timer wrong can leave the PC failing to boot, shutting down at the wrong time, or draining the vehicle battery. Stay within the recommended range unless you have a specific reason not to.

You can change timers from the GUI or the CLI. Either way, the values you type are in the connected platform’s own unit, and pcu reads the value back after writing to confirm it took.

In the GUI, use the Ignition page. Each timer has a description, its recommended range and default, quick-select presets, and a custom value box. Saving asks you to confirm and then reads the value back to check the write took.

From the CLI, pcu-cli ign shows the current values. On a CQ20:

$ pcu-cli ign
pcu v1.1.0  - In-CarPC CQ20 Ignition
----------------------------------------
  MCU Firmware        : 12
  Ignition Mode       : On
  Anti-Crank Delay    : 6s               IGN on to DC power
  Boot Delay          : 4s               DC on to power button
  Shutdown Delay      : 300s (5m)        IGN off to ACPI shutdown
  Force Off Timeout   : 120s (2m)        Hard power cut if OS hangs

On a CQ40N the same command lists that platform’s five timers instead, and adds a Delay Unit line showing whether they are being counted in minutes or seconds.

Set a timer with pcu-cli ign set <timer> <value>. It asks you to confirm, writes the value, and reads it back:

$ pcu-cli ign set sw-off-delay 120
Write Shutdown Delay = 120s (2m)? [y/N] y
  Shutdown Delay: 120s (2m) - verified

A value outside the timer’s range is rejected before anything is written, and the error shows the default and the recommended range:

$ pcu-cli ign set sw-off-delay 9000
ERROR: Shutdown Delay must be 3-7200s. Got: 9000
  Default: 300s (5m)  |  Recommended: 30-300s

For the full command surface, exit codes, and scripting notes, see the Command Reference.

Ignition mode

The ignition mode decides whether the MCU runs the automatic power sequence at all. It is a CQ20 feature. pcu shows it, but only for reading.

Ignition mode is read-only

The CQ20 MCU firmware does not support changing the ignition mode from software, so neither the app nor the CLI offers a way to set it. The mode is changed with the physical switch on the ignition module board.

The CQ40N series has no ignition mode setting at all, so nothing is shown for it there.