Hello!
I'm a student and I'll be using a Teensy 4.0 in the electronics design for a CubeSat. I'm worried about potential latch up issues on the microcontroller caused by single event upsets. Previous flight heritage dictates that space ready electronics boards utilize a hardware configured watchdog circuit to monitor the microcontroller. Ideally, I would use a backup microcontroller, or a backup FPGA, or a radiation hardened microcontroller, but unfortunately the design is time and money constrained.
After reading some other forum posts here, it seemed like there was a bunch of software solutions. However, I am looking to avoid anything software related to have a totally hardware based backup. I've thus designed the below circuit (see attached photo) using a MIC1832 watchdog I.C. Since there is no reset pin on the Teensy 4.0, the watchdog will short the power input to the Teensy. It seems that Paul recommended this in another forum post.
My main concern is timing characteristics. The watchdog timer is 1.2 seconds. If the watchdog triggers, then the RST pin will go high for 250ms. I'm wondering two things about timing:
1) Will the 250ms short on the power line be enough to reset the microcontroller? The input voltage is DC.
2) Will the microcontroller be able to reboot in the 1.2 seconds and start sending the /ST signal before the watchdog trips again? I don't want it to get stuck in a constant loop.
This is my first time designing a watchdog circuit, and my first time designing with the Teensy 4.0. I'm also quite new to electrical engineering, so please feel free to explain even basic concepts if there is something I am missing. Thanks you all so much!
Jashan
I'm a student and I'll be using a Teensy 4.0 in the electronics design for a CubeSat. I'm worried about potential latch up issues on the microcontroller caused by single event upsets. Previous flight heritage dictates that space ready electronics boards utilize a hardware configured watchdog circuit to monitor the microcontroller. Ideally, I would use a backup microcontroller, or a backup FPGA, or a radiation hardened microcontroller, but unfortunately the design is time and money constrained.
After reading some other forum posts here, it seemed like there was a bunch of software solutions. However, I am looking to avoid anything software related to have a totally hardware based backup. I've thus designed the below circuit (see attached photo) using a MIC1832 watchdog I.C. Since there is no reset pin on the Teensy 4.0, the watchdog will short the power input to the Teensy. It seems that Paul recommended this in another forum post.
My main concern is timing characteristics. The watchdog timer is 1.2 seconds. If the watchdog triggers, then the RST pin will go high for 250ms. I'm wondering two things about timing:
1) Will the 250ms short on the power line be enough to reset the microcontroller? The input voltage is DC.
2) Will the microcontroller be able to reboot in the 1.2 seconds and start sending the /ST signal before the watchdog trips again? I don't want it to get stuck in a constant loop.
This is my first time designing a watchdog circuit, and my first time designing with the Teensy 4.0. I'm also quite new to electrical engineering, so please feel free to explain even basic concepts if there is something I am missing. Thanks you all so much!
Jashan