Products > Test Equipment
finding short on motherboards with a shorty (with display)
kripton2035:
@jdobry: please make a new thread with your device details... this thread is for the shorty-with-display. thanks.
Miti:
Hi jdobry,
Our troubleshooters liked your project so we created a 10 up panel and assembled 10 boards on the SMT line. I programmed them with v1.02.02 and everything looks good but I have an issue with the I2C communication, I think. The OLED goes crazy after some time, between few seconds and about a minute. The display and sound freeze with a broken display or not. The SW is still running because I can turn it off with a long press and it respond with a long beep. My guess is that the I2C is too fast for some OLEDs. Is it possible to slow it down a bit?
Thanks ,
Miti
Kean:
--- Quote from: Miti on January 16, 2024, 09:17:08 pm ---Hi jdobry,
Our troubleshooters liked your project so we created a 10 up panel and assembled 10 boards on the SMT line. I programmed them with v1.02.02 and everything looks good but I have an issue with the I2C communication, I think. The OLED goes crazy after some time, between few seconds and about a minute. The display and sound freeze with a broken display or not. The SW is still running because I can turn it off with a long press and it respond with a long beep. My guess is that the I2C is too fast for some OLEDs. Is it possible to slow it down a bit?
Thanks ,
Miti
--- End quote ---
Without seeing them, I doubt the I2C bus is "too fast" or the ones Jiri made would not have worked. I guess the OLEDs could be marginal.
As a troubleshooting step, I would look at the I2C signals on a scope. That would confirm the speed and shape of the I2C signals.
But even before that, I see on the schematic that the I2C pullups are 10k which is a bit high for 3.3V. Maybe try decreasing R10 and R11 to something in the range of 3k3 to 4k7.
I haven't made any of these yet, but I am about to order some of the PCBs and parts.
Miti:
--- Quote from: Kean on January 17, 2024, 10:40:02 am ---I doubt the I2C bus is "too fast" or the ones Jiri made would not have worked. I guess the OLEDs could be marginal.
--- End quote ---
Yeap, another way of saying the same thing. Too fast for the OLED. He may have been lucky with very fast OLEDs, mine may be a bit slower.
I did play a bit with the pull ups, I soldered 4.7K in parallel with the 10K. First I soldered one on the SCL and the display didn't come on at all. Then I soldered on both SCL and SDA and it came back on but crashing again. I will post some scope screen shots.
Kean:
I assume you must have used SSD1306 based OLEDs to be compatible. The SSD1306 is specified to support up to 400kHz I2C.
Do you have a link to the OLEDs you bought?
I'm not a fan of TZT stores on AliExpress, but was planning to buy the suggested ones at https://www.aliexpress.com/item/32927682460.html
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