This describes the pins on the Raspberry Pi boards. Since the BCM2835 SOC internally uses different numbers (and these numbers differ between versions, the library internally translates this pin number to the correct number.

A GPIO pin can be either set to input mode, output mode or an alternative mode.

Either high or low.

This describes the address of an I2C slave.

Specifies the SPI data bit ordering.

This describes which Chip Select pins are asserted (used in SPI communications).

Clock polarity (CPOL) for SPI transmissions.

Clock phase (CPHA) for SPI transmissions.

Any IO computation that accesses the GPIO pins using this library should be wrapped with this function; ie withGPIO $ do foo. It prepares the file descriptors to devmem and makes sure everything is safely deallocated if an exception occurs. The behavior when accessing the GPIO outside of this function is undefined.

Sets the pin to either Input or Output mode.

Returns the current state of the specified pin.

Sets the specified pin to either True or False.

Any IO computation that uses the I2C bus using this library should be wrapped with this function; ie withI2C $ do foo. It prepares the relevant pins for use with the I2C protocol and makes sure everything is safely returned to normal if an exception occurs. If you only use the GPIO pins for I2C, you can do withGPIO . withI2C $ do foo and it will work as expected. WARNING: after this function returns, the I2C pins will be set to Input, so use setPinFunction if you want to use them for output.

Sets the clock divider for (and hence the speed of) the I2C bus.

Sets the baud rate of the I2C bus.

Writes the data in the ByteString to the specified I2C Address. Throws an IOException if an error occurs.

Reads num bytes from the specified Address. Throws an IOException if an error occurs.

Writes the data in the ByteString to the specified Address, then issues a "repeated start" (with no prior stop) and then reads num bytes from the same Address. Necessary for devices that require such behavior, such as the MLX90620.

Any IO computation that uses the AUX SPI functionality using this library should be wrapped with this function; ie withAUXSPI $ do foo. It prepares the relevant pins for use with the SPI protocol and makes sure everything is safely returned to normal if an exception occurs. If you only use the GPIO pins for SPI, you can do withGPIO . withAUXSPI $ do foo and it will work as expected. WARNING: after this function returns, the SPI pins will be set to Input, so use setPinFunction if you want to use them for output.

Any IO computation that uses the SPI functionality using this library should be wrapped with this function; ie withSPI $ do foo. It prepares the relevant pins for use with the SPI protocol and makes sure everything is safely returned to normal if an exception occurs. If you only use the GPIO pins for SPI, you can do withGPIO . withSPI $ do foo and it will work as expected. WARNING: after this function returns, the SPI pins will be set to Input, so use setPinFunction if you want to use them for output.

Sets the chip select pin(s). When a transfer is made with transferSPI or transferManySPI, the selected pin(s) will be asserted during the transfer.

Set the bit order to be used for transmit and receive. The bcm2835 SPI0 only supports MSBFirst, so if you select LSBFirst, the bytes will be reversed in software. The library defaults to MSBFirst.

Sets the chip select pin polarity for a given pin(s). When a transfer is made with transferSPI or transferManySPI, the currently selected chip select pin(s) will be asserted to the LogicLevel supplied. When transfers are not happening, the chip select pin(s) return to the complement (inactive) value.

Sets the AUX SPI clock divider and therefore the SPI clock speed.

Sets the SPI clock divider and therefore the SPI clock speed.

Sets the SPI clock polarity and phase (ie, CPOL and CPHA)

Transfers one byte to and from the SPI slave. Asserts the CS2 pin during the transfer. Clocks the 8 bit value out on MOSI, and simultaneously clocks in data from MISO. Returns the read data byte from the slave.

Transfers one byte to and from the currently selected SPI slave. Asserts the currently selected CS pins (as previously set by chipSelectSPI) during the transfer. Clocks the 8 bit value out on MOSI, and simultaneously clocks in data from MISO. Returns the read data byte from the slave.

Transfers any number of bytes to and from the currently selected SPI slave, one byte at a time. Asserts the currently selected CS pins (as previously set by chipSelectSPI) during the transfer. Clocks 8 bit bytes out on MOSI, and simultaneously clocks in data from MISO.

Sets the PWM clock divisor, to control the basic PWM pulse widths.

Sets the mode of the given PWM channel, allowing you to control the PWM mode and enable/disable that channel

Sets the maximum range of the PWM output. The data value can vary between 0 and this range to control PWM output

Sets the PWM pulse ratio to emit to DATA/RANGE, where RANGE is set by setRangePWM.