You can use the I2C interface from the esp8266 to interface to the PSOC 4200 chip. It also has Uart and Spi interfaces.
Yeah I'm using UART in the PSoC for the interface.
Can you please elaborate more on how will I interface the esp8266 i.e which pins on esp will i connect to what pins of psoc.
Also if you have a sample code, can you please link it here or any source with a sample code with it.
It would be a great help.
Are you using the development board Psoc ble pioneer kit?
Yes.. I'm using PSoC 4200 BLE Pioneer Kit Development Board
We do not have an example with CY8CKIT-042. But you can have a look at the external link:https://hackaday.io/project/3250-cypress-psoc-4-esp8266-ws2812-rgb-xmas-lights
Hope this helps.