randomvibe
Well-known member
My project involves a kickstarter Teensy 3.6 connected to two SPI devices: (1) an LSM6DS3 IMU sensor, and (2) the ILI9341 display. The Teensy also drives a pair of 3A stepper drivers. The drivers are powered by the very inexpensive "Dr. Meter DC Power Supply PS-305DM" (30V, 5A).
The display SPI line is a 10 inch CAT5 internally-shielded cable. The IMU SPI line is a ~4 foot CAT6 wire-mesh-shielded cable. The stepper drivers are optoisolated. The Teensy setup ground plane is completely isolated.
Here's the problem. When the stepper drivers are unpowered, the Teensy 3.6 setup is rock solid. No IMU dropouts. No display problems. When the drivers are powered, the display intermittently scrambles the text. This is undoubtedly an EMI problem. I traced the issue to the power supply line, which is very long (~12 ft) and rolled-up on spool just a few inches from the Teensy setup. When I unspool the supply line and move it several feet away from the Teensy 3.6, it improves the situation, but the display still scrambles ocassionally. Reducing the CPU speed does not help.
When I swap in a Teensy 3.2 and leave all the system wiring in place, the setup is rock solid. Even if I spool-up the supply line near the setup, it's still rock solid. But my project needs more pins.
In desperation, I bought a Teensy 3.5 at Microcenter yesterday. When I swap it in, it's rock solid when the the supply line is unspooled. It does not need to be several feet away. However, if I spool it up right next to the display, EMI scrambles the display.
The kickstarter Teensy 3.6 appears to be very sensitive to EMI. Teensy 3.5 is definitely more stable. Teensy 3.2 is rock solid. Does this make sense to PRJC?
The display SPI line is a 10 inch CAT5 internally-shielded cable. The IMU SPI line is a ~4 foot CAT6 wire-mesh-shielded cable. The stepper drivers are optoisolated. The Teensy setup ground plane is completely isolated.
Here's the problem. When the stepper drivers are unpowered, the Teensy 3.6 setup is rock solid. No IMU dropouts. No display problems. When the drivers are powered, the display intermittently scrambles the text. This is undoubtedly an EMI problem. I traced the issue to the power supply line, which is very long (~12 ft) and rolled-up on spool just a few inches from the Teensy setup. When I unspool the supply line and move it several feet away from the Teensy 3.6, it improves the situation, but the display still scrambles ocassionally. Reducing the CPU speed does not help.
When I swap in a Teensy 3.2 and leave all the system wiring in place, the setup is rock solid. Even if I spool-up the supply line near the setup, it's still rock solid. But my project needs more pins.
In desperation, I bought a Teensy 3.5 at Microcenter yesterday. When I swap it in, it's rock solid when the the supply line is unspooled. It does not need to be several feet away. However, if I spool it up right next to the display, EMI scrambles the display.
The kickstarter Teensy 3.6 appears to be very sensitive to EMI. Teensy 3.5 is definitely more stable. Teensy 3.2 is rock solid. Does this make sense to PRJC?
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