# I2C QW/ST connector on motor 2040 - which pins?

**URL:** <https://forums.pimoroni.com/t/i2c-qw-st-connector-on-motor-2040-which-pins/22419>\
**Category:** Support\
**Created:** [June 29, 2023, 4:06pm UTC](https://forums.pimoroni.com/t/i2c-qw-st-connector-on-motor-2040-which-pins/22419 "2023-06-29T16:06:57Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![stephenp](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/stephenp/32/8898_2.png) [@stephenp](https://forums.pimoroni.com/u/stephenp)\
**Post date:** [June 29, 2023, 4:06pm UTC](https://forums.pimoroni.com/t/i2c-qw-st-connector-on-motor-2040-which-pins/22419/1 "2023-06-29T16:06:57Z")

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I am writing some code to interface via I2C (with the motor2040 as slave), but I don’t know which pins the Qw/ST connector connects to. Can anybody please point me to a diagram?

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**Author:** ![alphanumeric](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/alphanumeric/32/2729_2.png) [@alphanumeric](https://forums.pimoroni.com/u/alphanumeric)\
**Post date:** [June 29, 2023, 4:56pm UTC](https://forums.pimoroni.com/t/i2c-qw-st-connector-on-motor-2040-which-pins/22419/2 "2023-06-29T16:56:08Z")

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It uses GP 20 for SDA and GP 21 for SCL  
`i2c = PimoroniI2C(sda=(20), scl=(21))` should work?

There is a link to the schematic on its shop page.  
[motor2040.sch (shopify.com)](https://cdn.shopify.com/s/files/1/0174/1800/files/motor2040_schematic.pdf?v=1655385574)

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**Author:** ![bablokb](https://avatars.discourse-cdn.com/v4/letter/b/ee59a6/32.png) [@bablokb](https://forums.pimoroni.com/u/bablokb)\
**Post date:** [June 30, 2023, 8:10am UTC](https://forums.pimoroni.com/t/i2c-qw-st-connector-on-motor-2040-which-pins/22419/3 "2023-06-30T08:10:29Z")

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> [@alphanumeric](#):
>
> `i2c = PimoroniI2C(sda=(20), scl=(21))` should work?

This is I2C in master-mode, so it won’t help you (although the pins are correct). For slave mode, you need some other libs. I posted some links in a different thread but can’t remember where. But you should be able to find it.

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**Author:** ![stephenp](https://sea2.discourse-cdn.com/flex016/user_avatar/forums.pimoroni.com/stephenp/32/8898_2.png) [@stephenp](https://forums.pimoroni.com/u/stephenp)\
**Post date:** [June 30, 2023, 3:26pm UTC](https://forums.pimoroni.com/t/i2c-qw-st-connector-on-motor-2040-which-pins/22419/4 "2023-06-30T15:26:37Z")

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Thank you both, yes the pins are correct. I found an article [here](https://python-academia.com/en/raspberry-pi-pico-slave/), which apart from the ads pestilence, was very helpful.