machine.FPGA – Functions to control the FPGA

The machine.FPGA class contains all of the functions to control the iCE40 FPGA. Import it using

from machine import FPGA

To see what’s contained inside the class you can use the help() command

help(FPGA)

Functions

FPGA.run()

• Brings the FPGA out of reset, and loads any binary stored in the flash

    PMIC.fpga_power(True) # Ensure the FPGA is powered on, in case you disabled it before
    FPGA.run()
  

• Ensure a valid FPGA binary is stored within the flash, otherwise the FPGA won’t configure

FPGA.reset()

• Resets the FPGA

FPGA.status()

• Gets the current status of the FPGA. Will return one of the following strings

  FPGA_RESET	The FPGA is currently held in reset
  FPGA_CONFIGURING	The FPGA is configuring and loading the binary from the flash
  FPGA_RUNNING	The FPGA is running

FPGA.irq()

• Once the FPGA is configured and running, the CDONE pin which tells us the state of the FPGA, can now be used as a user interrupt

• Similar to Pin.irq() it can be configured to execute a callback whenever the CDONE pin goes low (always a falling edge)

    # First set up a callback
    def myCallback():
        print("Do stuff")
  
    FPGA.run()
    FPGA.irq(myCallback)
  

FPGA.irq_disable()

• Disables the FPGA interrupt

FPGA.read(rxbuffer)

• Reads data from the FPGA over the internal SPI bus

    rx = bytearray(10) # Create a 10 byte buffer to read into
    FPGA.read(rx) # Reads 10 bytes over the SPI bus
  
    # The buffer can be printed, showing what was received
    rx
    # Will print out
    bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
  

FPGA.write(txBuffer)

• Writes data to the FPGA over the internal SPI bus

    tx = [1, 2, 3, 4, 5] # Create an array of 5 bytes to send
    tx = "\x01\x02\x03\x04\x05" # The buffer can also be created as a string
  
    FPGA.write(tx) # Sends the 5 bytes from the tx buffer
  

FPGA.read_write(rxBuffer, txBuffer)

• Simultaneously reads and writes data

    # rx and tx are the same as before
    FPGA.read_write(rx, tx) # Read 10 bytes, and write 5 bytes