Power-On Reset for Teensy 4.1 Without Removing USB

[rajrana03]

Hi, I need to perform a Power-On reset on T4_1 to fully restart it without unplugging the USB.

Problem:
In my industrial setup, EMI bursts occasionally cause my SPI sensors to output garbage data. A full power cycle always recovers them, but a software reset (SCB_AIRCR = 0x05FA0004) only works sometimes.

Setup:

• MPU9250 (SPI) and IIS3DWB (SPI1) on T4_1
• Data sent to PC via Dual Serial (Serial for data, SerialUSB1 for commands)
• Sensors are ~3m away from T4_1, connected via a 10-core shielded cable

What I Tried:

• Software reset: partial recovery, but not always
• SPI.begin()/end(): no effect
• Improved cables: reduced errors but didn’t eliminate them
• Power cycling (USB unplug/replug) always restores sensors

Is there a way to fully restart T4_1 without physically removing power? Any other suggestions?

Relevant links:

• T4 Software Restart Discussion
• Power-On Reset in Ref Manual

 

[PaulStoffregen]

Does Teensy have a way to fully reset those sensor chips after it reboots?

 

[rajrana03]

Does Teensy have a way to fully reset those sensor chips after it reboots?

No. Sensor power cut from teensy doesn't recover the sensors but removing USB and reconnecting teensy cause 100% recovery.

 

[Angelo]

SPI and 3m cable ?!? What SPI clock frequency do you use ??? SPI on long line is not a good idea. Even tenth of centimeters could be hard.

As you have 10 wires, you can try to implement RS422 interface for each one of Clock, MISO, MOSI and CS1.

 

[rajrana03]

SPI and 3m cable ?!? What SPI clock frequency do you use ???

Yes, 8MHz and SPI works properly.

As you have 10 wires, you can try to implement RS422 interface for each one of Clock, MISO, MOSI and CS1.

I've found out that using Cat 6 SFTP LAN Cable (4pairs-8core), helps in reducing to minimal errors but not eliminate it.