# UART communication

Source: https://forum.modalai.com/topic/2713/uart-communication
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2023-10-03 14:04:08 UTC by SHofmeester
Replies: 1 · Views: 601

## SHofmeester · 2023-10-03 14:04:08 UTC

Hi,

We want to connect an arduino to the J10 UART.
When we try `voxl-uart-loopback -d 7`, it fails.
When we use 'voxl-i2c scan 7 400000`, it recognizes the device (besides the UART TX and RX we connected the SDA and SCL as well)

We also tried it with a GPS, so that we could be sure it wasn't the arduino code, but it had the same result: uart failed and i2c was recognized.

``` 
/ # serial-read-teensy -d 7
INITIALIZING
Sending 10 bytes:
0123456789
Transfer should take ~1736us, sleeping for 6736us (+5000us overhead)
Reading back data...
ERROR: voxl_uart_read 0 bytes, expected 10
closing uart bus
FAIL
```

Can you help us with this?

Thanks in advance!

## Reply by Eric Katzfey (ModalAI staff) · 2023-10-03 15:48:50 UTC

@SHofmeester J10 on the VOXL2 is a SPI port. https://docs.modalai.com/voxl2-connectors/#j10---external-spi