Pullup resistors on I2C, why?

hallard / WeMos-Lora

ESP8266 WeMos Shield for HopeRF RFM95 RFM96 RFM98 Lora module

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Pullup resistors on I2C, why? #19

Open atrent opened 5 years ago

atrent commented 5 years ago

Hi, is there a motive for R1 and R2 (pullup resistors for SDA and SCL)? I'd like to use Wemos pins D1 and D2 for a SoftwareSerial... Thanks

pfeerick commented 5 years ago

Because I²C needs pullups.

If you're not going to use I²C, don't put them on.

atrent commented 5 years ago

thanks for the reply (and sorry for the delay in my follow up)

I actually have an old version of the shield (see photo) and I've checked now that R1, R2 and the 24AA... chip are NOT present, so the fact that I could not activate a SoftwareSerial on those pins is to be investigated more, my bad

2019-07-10 08 38 51