class SoftSPI – Software Implementation of SPI Bus Protocol
2023-08-31
This class provides bus protocol of Serial Peripheral Interface (SPI).
EC600E/EC800E module supports this feature.
Constructor
machine.SoftSPI
class machine.SoftSPI(gpio_clk, gpio_cs, gpio_mosi, [gpio_miso],[wire_type],[speed],[mode],[cs_active_lvl])
Parameter
gpio_clk
- Integer type. The GPIO corresponding to the CLK.gpio_cs
- Integer type. The GPIO corresponding to the CS.gpio_mosi
- Integer type. The GPIO corresponding to the MOSI.[gpio_miso]
- Integer type. The GPIO corresponding to the MISO. For 3-wire SPI, this parameter can be omitted and the MOSI can be used for receiving and sending data.[wire_type]
- Integer type. Set SPI to 3-wire SPI or 4-wire SPI.WIRE_3
: 3-wire SPI.WIRE_4
: 4-wire SPI. Default value: 4-wire SPI.[speed]
- Integer type. Transmission speed.0
: 50 kHz.1
: 100 kHz. Default value: 100 kHz.[mode]
- Integer type. SPI mode. Range:0
–3
. Default value:0
.0
: CPOL=0, CPHA=01
: CPOL=0, CPHA=12
: CPOL=1, CPHA=03
: CPOL=1, CPHA=1[cs_active_lvl]
- Integer type. CS active level.LOW
: low level.HIGH
: high level. Default value: low level.
Return Value
The object created - Successful execution
Error - Failed execution
Example
from machine import SoftSPI
# Create a 4-wire SPI object. CLK: GPIO14. CS: GPIO11. MOSI: GPIO12. MISO: GPIO13. SPI mode: 0. Transmission speed: 100 kHz. CS: low level.
spi=SoftSPI(gpio_clk=SoftSPI.GPIO14,gpio_cs=SoftSPI.GPIO11,gpio_mosi= SoftSPI.GPIO12,gpio_miso= SoftSPI.GPIO13)
# Create a 4-wire SPI object. CLK: GPIO14. CS: GPIO11. MOSI: GPIO12. MISO: GPIO13. SPI mode: 1. Transmission speed: 50 kHz. CS: high level.
spi=SoftSPI(gpio_clk=SoftSPI.GPIO14,gpio_cs=SoftSPI.GPIO11,gpio_mosi=SoftSPI.GPIO12,gpio_miso=SoftSPI.GPIO13,
speed=0,mode=1,cs_active_lvl=SoftSPI.HIGH)
# Create a 3-wire SPI object. CLK: GPIO14. CS: GPIO11. MOSI: GPIO12. SPI mode: 0. Transmission speed: 100 kHz. CS: low level.
spi=SoftSPI(gpio_clk=SoftSPI.GPIO14,gpio_cs=SoftSPI.GPIO11,gpio_mosi= SoftSPI.GPIO12,wire_type= SoftSPI.WIRE_3)
# Create a 3-wire SPI object. CLK: GPIO14. CS: GPIO11. MOSI: GPIO12. SPI mode: 2. Transmission speed: 50 kHz. CS: high level.
spi=SoftSPI(gpio_clk=SoftSPI.GPIO14,gpio_cs=SoftSPI.GPIO11,gpio_mosi=SoftSPI.GPIO12,wire_type=SoftSPI.WIRE_3,
speed=0,mode=2,cs_active_lvl=SoftSPI.HIGH)
Methods
SoftSPI.read
SoftSPI.read(recv_data, datalen)
This method reads data.
Parameter
recv_data
- Bytearray type. An array used to receive data.datalen
- Integer type. Length of the data to be read.
Return Value
0
SoftSPI.write
SoftSPI.write(data, datalen)
This method writes data.
Parameter
data
- Bytes type. Data to be written.datalen
- Integer type. Length of data to be written.
Return Value
0
SoftSPI.write_read
SoftSPI.write_read(r_data, data, datalen)
This method writes and reads data.
Parameter
r_data
- Bytearray type. An array used to receive data.data
- Bytes type. Data to be sent.datalen
- Integer type. Length of data to be read.
Return Value
0
For 3-wire SPI, in the communicating process, MOSI is set to the output mode first and data will be sent. And then MOSI is set to the input mode and the datalen bytes of data will be read.
Example
Please use this method with the peripherals.
Example for 4-wire SPI
from machine import SoftSPI
spi=SoftSPI(gpio_clk=SoftSPI.GPIO14,gpio_cs=SoftSPI.GPIO11,gpio_mosi= SoftSPI.GPIO12,gpio_miso= SoftSPI.GPIO13)
if __name__ == '__main__':
r_data = bytearray(5) # Create a buffer for receiving data
data = b"world" # Test data
spi.write_read(r_data, data, 5) # Write and receive data
spi.read(r_data,5) # Receive data to r_data
spi.write(data,5)# Send data
Example for 3-wire SPI
from machine import SoftSPI
spi=SoftSPI(gpio_clk=SoftSPI.GPIO14,gpio_cs=SoftSPI.GPIO11,gpio_mosi= SoftSPI.GPIO12,wire_type= SoftSPI.WIRE_3)
if __name__ == '__main__':
r_data = bytearray(5) # Create a buffer for receiving data
data = b"world" # Test data
spi.write_read(r_data, data, 5) # Write and receive data
spi.read(r_data,5) # Receive data to r_data
spi.write(data,5)# Send data