Espressif ESP32-S2 User Manual

Chapter 2. API Reference
4. Call essl_init() to do initialization of the SDIO part.
5. Call essl_wait_for_ready() to wait for the slave to be ready.
ESP SPI Slave
Note: If you are communicating with the ESP SDIO Slave device through SPI interface, you should use the SDIO
interface instead.
Hasn’t been supported yet.
APIs
After the initialization process above is performed, you can call the APIs below to make use of the services provided
by the slave:
Tohost Interrupts (optional)
1. Call essl_get_intr_ena() to know which events will trigger the interrupts to the master.
2. Call essl_set_intr_ena() to set the events that will trigger interrupts to the master.
3. Call essl_wait_int() to wait until interrupt from the slave, or timeout.
4. When interrupt is triggered, call essl_get_intr() to know which events are active, and call
essl_clear_intr() to clear them.
Frhost Interrupts
1. Call essl_send_slave_intr() to trigger general purpose interrupt of the slave.
TX FIFO
1. Call essl_get_tx_buffer_num() to know how many buffers the slave has prepared to receive data
from the master. This is optional. The master will poll tx_buffer_num when it try to send packets to the slave,
until the slave has enough buffer or timeout.
2. Call essl_send_paket() to send data to the slave.
RX FIFO
1. Call essl_get_rx_data_size() to know how many data the slave has prepared to send to the master.
This is optional. When the master tries to receive data from the slave, it will update the rx_data_size for once,
if the current rx_data_size is shorter than the buffer size the master prepared to receive. And it may poll the
rx_data_size if the rx_dat_size keeps 0, until timeout.
2. Call essl_get_packet() to receive data from the slave.
Reset counters (Optional) Call essl_reset_cnt() to reset the internal counter if you find the slave has reset
its counter.
Application Example
The example below shows how ESP32-S2 SDIO host and slave communicate with each other. The host use the ESSL
SDIO.
peripherals/sdio.
Please refer to the specific example README.md for details.
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Espressif ESP32-S2 Specifications

General

Brand	Espressif
Model	ESP32-S2
Category	Single board computers
Language	English