Adding wifi to STM32

ESP8266 is by far the easiest, IMO.

> I collect large amounts of data from several sensors (high sample rate) and store the data in a micro sd card. When measure is over I would like to send the raw data to a phone using WIFI (tried bluetooth but speed is not enough for me).

I don't think you're going to find an example that has exactly what you want. It's a learning process. Try to replicate an existing example, or take parts from it and go from there.

I have some doubts that storing "large amounts of data" to a SD card would work. SD cards can have write latencies up to 250 ms. How long does it take for the samples to fill up the 80 kBytes of RAM on the L152RE?

How large are exactly those amounts of data?

The ESP8266 should be avoided when in the 8 pin board, and here's why, especially if you use an RTOS. The UART/USART in the ST chips has effectively no fifo at all, and when you task switch, you can miss data or overrun the USART data register. While the ESP chip does have flow control, those pins are not brought out on the 8 pin board. So to avoid missing data, you need either flow control or you need a FIFO that's big enough to hold enough receive data (where the problem is) during task switching times.

The ESP-12 form factor (the multiple pin version of the ESP chip on a carrier) does have flow control, so if the USART can be enabled with flow control, it's possible that the internal USART will work. That is not the approach I took. I used a separate I2C chip, the SC16IS750, which is a serial to I2C chip. I2C plays nice with an operating system. The SC16 has built in flow control and a 64 byte FIFO. The SC16 flow control lines can connect directly to the ESP.

The ESP can be set up peer to peer, with a serial passthrough of data. That's effectively writing to a serial port and having the data come out the other end as a serial port, which your program can access as a socket.

That might be a good start.