# SPI from STM32 to ESP not working at all **URL:** \ **Category:** Networking, Protocols, and Devices\ **Created:** [September 19, 2019, 6:05pm UTC](https://forum.arduino.cc/t/spi-from-stm32-to-esp-not-working-at-all/611584 "2019-09-19T18:05:02Z")\ **Posts on this page:** 1\ **Showing post:** 2
**Author:** ![Idahowalker](https://dub1.discourse-cdn.com/arduino/user_avatar/forum.arduino.cc/idahowalker/32/238858_2.png) [@Idahowalker](https://forum.arduino.cc/u/Idahowalker)\ **Post date:** [September 19, 2019, 9:09pm UTC](https://forum.arduino.cc/t/spi-from-stm32-to-esp-not-working-at-all/611584/2 "2019-09-19T21:09:14Z")
> The master device clock polarity configuration of ESP8266 SPI slave communication should be set with idle low power, rising edge sampling and falling edge data transformation. The ESP8266 will not be looking for SPI data during the time SS is low. Starting with the time of SS rising the ESP8266 will read the incoming data. During the time of falling of the SS the data will be made available for use. The ESP32 can do duplex, as in receive data and transmit data at the same time. You might want to get an inexpensive logic analyzer as a troubleshooting tool for SPI. I found that the HiLetgo USB Logic Analyzer does a good job for its low price. I use ESP32's and the ESP32 SPI API, mostly because many SPI libraries do not take full advantage of the ESP32's SPI capability. I have not used a ESP8286. I recommend looking to see if the ESP266 has a SPI Slave API. --- _[View the full topic](https://forum.arduino.cc/t/spi-from-stm32-to-esp-not-working-at-all/611584)._