2404257_en-US

SC18IS606 - reading back issue

Hello,

We have I2C to SPI converter SC18IS606 manufactured by NXP. We are using Raspberry Pi to write and read data to SC18IS606 through I2C. The device SC18IS606 is shown listed in the Raspberry Pi OS terminal and is detected through “i2cdetect -y 1” command in the terminal with correct address.

As a simple test, we tried write operation (set/clear) to the GPIO 0 to 2 and make them toggle in the loop with some delay in between. This part is working.

But when we read back from the SC18IS606, it reads 0x80 instead 0x00.

Latter we tied the pins MISO and MOSI together making SPI loop back using a jumper wire. We are sending patterns 0x00 through 0x07 to SPI. The read back data we got is 0x80 through 0x87.

The MSB is always 1 when we read back SPI in the loop back test.

We have tested two SC18IS606 chips which we bought from Mouser and we got the same result.

Any idea what could be the issue ? How to fix ?