A thin layer over USB to communicate with FTDI chips.

This library enables you to communicate with FTDI devices. It is implemented as a lightweight wrapper around the usb library.

FTDI

This library enables you to communicate with FTDI USB devices. It is implemented as a lightweight wrapper around the usb library.

See bindings-libusb for instructions to install libusb.

Build Source (Ubuntu)

$ sudo apt install libusb-1.0-0-dev
$ git clone https://github.com/standardsemiconductor/ftdi.git
$ cd ftdi/
$ cabal build
$ cabal test

Sample Usage

Find the first USB device matching the vendor ID and product ID:

import qualified System.USB as USB
import qualified Data.Vector as V (toList)
import Data.List (find)
import System.FTDI

data Failure = FailureNotFound
             | FailureOther

findUSBDevice 
  :: USB.VendorId 
  -> USB.ProductId 
  -> IO (Either Failure (USB.Device, USB.Ctx))
findUSBDevice vendorId productId = do
  ctx <- USB.newCtx
  devDescs <- getDeviceDescs ctx
  return $ case fst <$> find (match . snd) devDescs of
    Nothing -> Left FailureNotFound
    Just dev -> Right (dev, ctx)
  where
    match :: USB.DeviceDesc -> Bool
    match devDesc =  USB.deviceVendorId  devDesc == vendorId
                  && USB.deviceProductId devDesc == productId

getDeviceDescs :: USB.Ctx -> IO [(USB.Device, USB.DeviceDesc)]
getDeviceDescs ctx = do
  devs <- V.toList <$> USB.getDevices ctx
  deviceDescs <- mapM USB.getDeviceDesc devs
  return $ zip devs deviceDescs

Setup an FT2232 FTDI device on interface A using MPSSE (Multi-Protocol Synchronous Serial Engine):

withFTDI 
  :: USB.VendorId 
  -> USB.productId
  -> (InterfaceHandle -> IO (Either Failure a) 
  -> IO (Either Failure a)
withFTDI vendorId productId action = findUSBDevice vendorId productId >>= \case
  Left failure -> return $ Left failure
  Right (usbDevice, ctx) -> do
    ftdiDevice <- fromUSBDevice usbDevice ChipType_2232H
    withDeviceHandle ftdiDevice $ \devHndl -> do
      resetUSB devHndl
      withDetachedKernelDriver devHndl Interface_A $
        withInterfaceHandle devHndl Interface_A $ \ifHndl -> do
          reset ifHndl
          purgeReadBuffer ifHndl
          purgeWriteBuffer ifHndl
          setLatencyTimer ifHndl 1
          setBitMode ifHndl 0xFF BitMode_MPSSE
          action ifHndl

References

• FTDI Website
• Application Note AN_108: Command Processor for MPSSE and MCU Host Bus Emulation Modes
• USB in a NutShell: Making sense of the USB standard.