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By williamlynn
Does the SerLCD (LCD-14072) have pullup resistors on the I2C pins(SDA,SCL)?
I'm using the SerLCD with QWIIC RTC(BOB-14558) and AS3935 LIGHTNING DETECTOR.
I don't need all the pullup resistors so if the SerLCD had pull-ups I would like to eliminate them. I want to keep the pullups on the LIGHTNING DETECTOR.

User avatar
By TS-Chris
Hi Bill.

The SerLCD does have pullup resistors on the I2C lines but there is no documented way on the board for removing them. I would recommend disabling the pullups on your other board since there is a jumper for that. If you really must remove the resistors from the LCD, you would need to trace the I2C lines on the board back to the pullups and manually desolder them.
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By TS-Mark
To expand a bit on TS-Chris's reply, I tested one of our RGB on Black SerLCDs and found that R7 and R6 are the pull-up resistors on this version. I would recommend double-checking with a multimeter to verify but if you need to disable them, those should be the ones to pull off the board.