diff --git a/STM32-Zombie.cabal b/STM32-Zombie.cabal
--- a/STM32-Zombie.cabal
+++ b/STM32-Zombie.cabal
@@ -1,15 +1,16 @@
 Name:          STM32-Zombie
-Version:       0.1.1
+Version:       0.2.0
 Category:      STM32, Hardware, Microcontroller
 License-File:  LICENSE
 Synopsis:      control a STM32F103 microcontroller
 Description:
-            This library turns a STM32F103 board into a powerful Haskell hackable
-            IO adapter. Features are GPIO pins, serial ports, SPI ports, DMA
-            ADC, timers,..
+            The STM32-Zombie library turns a STM32F103 board into a
+            powerful Haskell hackable IO adapter.
+            Features are GPIO pins, serial ports, SPI ports, DMA ADC, timers,..
             The library is modeled after the STMicroelectronics
-            STM32F10x Firmware Library.
-            The library has a rather low-level interface, which
+            STM32F10x Firmware Library but does not rely on any c-code or
+            cross-compilation
+            STM32-Zombie has a low-level interface, which
             allows one to control many details of the micro controller hardware
             and can also be used to build higher level abstraction.
             See the "App.Blink" module
diff --git a/src/App/ADC.hs b/src/App/ADC.hs
--- a/src/App/ADC.hs
+++ b/src/App/ADC.hs
@@ -8,12 +8,11 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- Example for the analog digital converter.
--- The ADC of the STM32 works best with DMA transfers.
+-- This module shows an example for using the analog digital converter.
+-- The ADC of the STM32 works best in combination with DMA transfers.
 -- This example turns the STM32 into a small digital storage oscilloscope.
--- As this works with DMA transfers, one can sample with precise timings
--- and  the block size and the sampling rate are not limited by the speed of
--- the Haskell code.
+-- Thanks to DMA transfers, one can sample with precise timings
+-- and sampling rate is not limited by the speed of the Haskell code.
 
 module App.ADC
 where
diff --git a/src/App/Blink.hs b/src/App/Blink.hs
--- a/src/App/Blink.hs
+++ b/src/App/Blink.hs
@@ -26,7 +26,7 @@
   resetHalt
   let (port,_) = led
   peripheralClockOn port
-  pinMode led $ GPOutPushPull Mhz_2
+  pinMode led $ GPOutPushPull MHz_2
   forever $ do
      pinHigh led
      delay 500000
diff --git a/src/App/DMABuffer.hs b/src/App/DMABuffer.hs
--- a/src/App/DMABuffer.hs
+++ b/src/App/DMABuffer.hs
@@ -8,7 +8,7 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- In this example the controller reads chars from the USART
+-- In this example, the controller reads chars from the USART
 -- and writes them to a RAM buffer using DMA.
 
 {-# LANGUAGE OverloadedStrings #-}
@@ -30,8 +30,8 @@
 
 
 -- | Initialize the Hardware and keep polling the DMA Buffer.
--- This loops for ever but the DMA transfer is only oneshot.
--- (after the buffer is full nothing interesting happens) 
+-- This function loops for ever.
+-- Though after the buffer is full nothing interesting happens.
 readCommDMA :: IO ()
 readCommDMA = runMI $ do
   initMI
@@ -42,7 +42,7 @@
   peripheralClockOn GPIOA
   peripheralClockOn AFIO
 
-  GPIO.pinMode (GPIOA,Pin_9) (AlternateOutPushPull Mhz_2)
+  GPIO.pinMode (GPIOA,Pin_9) (AlternateOutPushPull MHz_2)
   GPIO.pinMode (GPIOA,Pin_10) InputPullUp
 
   USART.enable USART1
@@ -78,9 +78,9 @@
 
 
 -- | Initialize the Hardware and keep polling the DMA Buffer.
--- This function uses a ring buffer that wraps over when filled up.
--- In this example DMA controller reads Bytes (8 Bit) from the UART
--- and writes half words (16 Bit) to then RAM or in other words
+-- 'uartRingBuffer' uses a ring buffer that wraps over when filled up.
+-- The DMA controller is configured to read Bytes (8 Bit) from the UART
+-- and write half words (16 Bit) to then RAM. This means
 -- it transfers a char and clears out the next byte to flag that this position
 -- in the buffer has been written.
 
@@ -95,7 +95,7 @@
   peripheralClockOn GPIOA
   peripheralClockOn AFIO
 
-  GPIO.pinMode (GPIOA,Pin_9) (AlternateOutPushPull Mhz_2)
+  GPIO.pinMode (GPIOA,Pin_9) (AlternateOutPushPull MHz_2)
   GPIO.pinMode (GPIOA,Pin_10) InputPullUp
 
   USART.enable USART1
diff --git a/src/App/LCD.hs b/src/App/LCD.hs
--- a/src/App/LCD.hs
+++ b/src/App/LCD.hs
@@ -6,9 +6,10 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- The LCD module has been copied from the hArduino package.
--- This is the System.Hardware.Arduino.Parts.LCD ((c) Levent Erkok)
--- with some minor adaption for STM32.
+-- The LCD module has been copied from
+-- System.Hardware.Arduino.Parts.LCD in the hArduino package.
+-- The original Author of this code is Levent Erkok.
+-- There have been some minor adaption for STM32.
 
 {-# LANGUAGE NamedFieldPuns #-}
 module App.LCD(
@@ -123,7 +124,7 @@
 initLCD :: LCD -> LCDController -> MI ()
 initLCD lcd c@Hitachi44780{lcdRS, lcdEN, lcdD4, lcdD5, lcdD6, lcdD7} = do
     debug "Starting the LCD initialization sequence"
-    mapM_ (\w -> GPIO.pinMode w $  GPOutPushPull Mhz_2)
+    mapM_ (\w -> GPIO.pinMode w $  GPOutPushPull MHz_2)
                 [lcdRS, lcdEN, lcdD4, lcdD5, lcdD6, lcdD7]
     -- Wait for 50ms, data-sheet says at least 40ms for 2.7V version, so be safe
     delay 50
diff --git a/src/App/RealTimeClock.hs b/src/App/RealTimeClock.hs
--- a/src/App/RealTimeClock.hs
+++ b/src/App/RealTimeClock.hs
@@ -12,7 +12,6 @@
 
 module App.RealTimeClock
 where
-import Control.Monad
 
 import STM32.API
 import qualified STM32.RTC as RTC
diff --git a/src/App/Stepper.hs b/src/App/Stepper.hs
--- a/src/App/Stepper.hs
+++ b/src/App/Stepper.hs
@@ -35,8 +35,8 @@
   initMI
   resetHalt
   peripheralClockOn port
-  pinMode dirWire $ GPOutPushPull Mhz_2
-  pinMode stepWire $ GPOutPushPull Mhz_2
+  pinMode dirWire $ GPOutPushPull MHz_2
+  pinMode stepWire $ GPOutPushPull MHz_2
   case dir of
     CW  -> pinHigh dirWire
     CCW -> pinLow dirWire
diff --git a/src/App/TestLCD.hs b/src/App/TestLCD.hs
--- a/src/App/TestLCD.hs
+++ b/src/App/TestLCD.hs
@@ -6,11 +6,10 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- The LCDDemo module has been copied from the hArduino package.
--- This is the System.Hardware.Arduino.Parts.TestLCD module
--- with some minor adaption for STM32.
--- System.Hardware.Arduino.Parts.TestLCD is copyright by Levent Erkok
--- 
+-- The LCDDemo module has been copied from
+-- System.Hardware.Arduino.Parts.TestLCD in the hArduino package.
+-- The original Author of this code is Levent Erkok.
+-- There have been some minor adaption for STM32. 
 
 module App.TestLCD
 where
diff --git a/src/App/TimerDMA.hs b/src/App/TimerDMA.hs
--- a/src/App/TimerDMA.hs
+++ b/src/App/TimerDMA.hs
@@ -10,8 +10,8 @@
 --
 -- This example show the combination of hardware timers with hardware DMA.
 -- Timer 4 triggers DMA1_Channel7 and the DMA writes data to the USART.
--- Instead of the USART its also possible to write to any other periveral.
--- Applications are wave form generation or any hard-real-time control. 
+-- Instead of the USART its also possible to write to any other peripheral.
+-- Applications are wave-form-generation or hard-real-time control. 
 
 module App.TimerDMA
 where
diff --git a/src/App/WS1228B.hs b/src/App/WS1228B.hs
--- a/src/App/WS1228B.hs
+++ b/src/App/WS1228B.hs
@@ -8,11 +8,12 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- The WS1228Bs are popular RGB LED controllers for colorful decorations and
--- mood lights etc.
--- For proper operation the WS1228B requires fast and acurate timing.
+-- The popular WS1228B module consists of a RGB LED and an included LED controller.
+-- Many WS1228B modules can be chained up to build LED strips
+-- for colorful decorations, mood lights etc.
+-- For proper operation the WS1228B requires fast and accurate timing.
 -- The example works with combination of SPI and DMA.
--- With the SPI port it is possible to shift out a raw bitstream.
+-- With the SPI port it is possible to shift out a raw bit-stream.
 -- (i.e. play a one-bit sampled wave-form).
 -- (This is not possible with the USART because the USART would add start and stop bits)
 
@@ -34,11 +35,11 @@
 testLEDs :: IO ()
 testLEDs = sendLEDs [red,green,blue,black,white]
 
--- | turn off the first 30 LEDs (== set the color to black black)
+-- | turn off the first 30 LEDs (== set the color to black)
 ledsOff30 :: IO ()
 ledsOff30 = sendLEDs $ replicate 30 black
 
--- | set the LEDs to a list of colors.
+-- | set the LED strip to a list of colors.
 sendLEDs :: [RGB] -> IO ()
 sendLEDs colors = runMI $ do
   initSPI
@@ -76,7 +77,7 @@
     (b3,b2,b1) = lineCodeWord8 b
 
 -- | Encode an Word8 according to the WS1228B line code.
--- each bit get extended to three bits
+-- Each data bit is extended to a three bit line code.
 lineCodeWord8 :: Word8 -> (Word8,Word8,Word8)
 lineCodeWord8 b = (c1,c2,c3)
   where
@@ -128,8 +129,8 @@
   peripheralClockOn GPIOB
   peripheralClockOn GPIOC
   peripheralClockOn SPI2
-  pinMode led $ GPOutPushPull Mhz_2
-  pinMode spi_mosi $ GPIO.AlternateOutPushPull Mhz_2
+  pinMode led $ GPOutPushPull MHz_2
+  pinMode spi_mosi $ GPIO.AlternateOutPushPull MHz_2
   SPI.init SPI2 spiConfig
   bitSet SPI2 CR2_TXDMAEN
 
@@ -162,7 +163,7 @@
 
   return ()
 
--- | Animate LEDs and show some wave like lighting pattern
+-- | Animate a LED strip and show some wave-like lighting pattern.
 testWave :: IO ()
 testWave = runMI $ do
   initSPI
diff --git a/src/STM32/API.hs b/src/STM32/API.hs
--- a/src/STM32/API.hs
+++ b/src/STM32/API.hs
@@ -9,7 +9,7 @@
 -- Portability :  GHC-only
 --
 -- The general part of the API.
--- The module for the periveral (GPIO, USART,ADC,..) is included separately.
+-- The module for the peripheral (GPIO, USART,ADC,..) has to be imported separately.
 
 module STM32.API
 (
diff --git a/src/STM32/DAC.hs b/src/STM32/DAC.hs
--- a/src/STM32/DAC.hs
+++ b/src/STM32/DAC.hs
@@ -8,9 +8,9 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- Digital Analog Converters
+-- Digital Analog Converters.
 -- This is untested.
--- The cheap STM32F103C8T6 boards don't hava a DAC included.
+-- The cheap STM32F103C8T6 boards don't have a built-in DAC.
 {-# LANGUAGE OverloadedStrings #-}
 module STM32.DAC
 where
diff --git a/src/STM32/DMA.hs b/src/STM32/DMA.hs
--- a/src/STM32/DMA.hs
+++ b/src/STM32/DMA.hs
@@ -8,11 +8,12 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- Direct Memory Access
--- The DMA controller is one of the coolest features of STM32Fxxx
+-- 
+-- The direct memory access (DMA)
+-- controller is one of the coolest features of STM32Fxxx
 -- micro controllers. 
--- For example with DMA one can sample analog signals at a fast and precise
--- sampling rate.
+-- For example, one can sample signals at a fast and precise
+-- sampling rate or generate wave-form patterns using DMA transfers.
 -- DMA transfers run completely independent and in parallel
 -- from the CPU or the Haskell code.
 
diff --git a/src/STM32/GPIO.hs b/src/STM32/GPIO.hs
--- a/src/STM32/GPIO.hs
+++ b/src/STM32/GPIO.hs
@@ -36,16 +36,16 @@
 pinLow w = pinOut w False
 
 data Speed
-  = Mhz_10
-  | Mhz_2
-  | Mhz_50
+  = MHz_10
+  | MHz_2
+  | MHz_50
   deriving (Eq,Ord,Show)
 
 instance ToBitField Speed where
   toBitField s = case s of
-    Mhz_10 -> "01"
-    Mhz_2  -> "10"
-    Mhz_50 -> "11"
+    MHz_10 -> "01"
+    MHz_2  -> "10"
+    MHz_50 -> "11"
         
 data PinMode
   = GPOutPushPull Speed
diff --git a/src/STM32/I2C.hs b/src/STM32/I2C.hs
--- a/src/STM32/I2C.hs
+++ b/src/STM32/I2C.hs
@@ -8,7 +8,7 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- Untested work in progress
+-- Untested // Work in progress
 {-# LANGUAGE OverloadedStrings #-}
 module STM32.I2C
 where
diff --git a/src/STM32/MachineInterface.hs b/src/STM32/MachineInterface.hs
--- a/src/STM32/MachineInterface.hs
+++ b/src/STM32/MachineInterface.hs
@@ -8,9 +8,9 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 -- 
--- At the moment there is just one implementation for the MachineInterface
+-- At the moment, there is just one implementation for the MachineInterface
 -- namely STM32.MachineInterfaceSTLinkUSB.
--- All direct communication with the microcontroller runs through this API.
+-- All direct communication with the micro controller runs through this API.
 -- 
 
 module STM32.MachineInterface
diff --git a/src/STM32/MachineInterfaceSTLinkUSB.hs b/src/STM32/MachineInterfaceSTLinkUSB.hs
--- a/src/STM32/MachineInterfaceSTLinkUSB.hs
+++ b/src/STM32/MachineInterfaceSTLinkUSB.hs
@@ -8,10 +8,12 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 -- 
--- This is the (internal) API for communitions over ST-Link USB dongles.
+-- STM32.MachineInterfaceSTLinkUSB is the (internal)
+-- API for communication with the STM32Fxxx boards
+-- All communication runs through these function.
 -- The main driver for ST-Link USB dongles is in the STLinkUSB package.
--- This module contains some small wrappers for functions from STM32.STLinkUSB
--- module.
+-- This module contains some small wrappers for functions from STM32.STLinkUSB.
+--
 
 module STM32.MachineInterfaceSTLinkUSB
 (
diff --git a/src/STM32/RCC.hs b/src/STM32/RCC.hs
--- a/src/STM32/RCC.hs
+++ b/src/STM32/RCC.hs
@@ -8,8 +8,8 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 --
--- Clock control
--- Resetting parts of the hardware.
+-- Clock control and
+-- resetting parts of the hardware.
 
 {-# LANGUAGE OverloadedStrings #-}
 module STM32.RCC
diff --git a/src/STM32/RTC.hs b/src/STM32/RTC.hs
--- a/src/STM32/RTC.hs
+++ b/src/STM32/RTC.hs
@@ -1,3 +1,15 @@
+----------------------------------------------------------------------------
+-- |
+-- Module      :  STM32.RTC
+-- Copyright   :  (c) Marc Fontaine 2017
+-- License     :  BSD3
+-- 
+-- Maintainer  :  Marc.Fontaine@gmx.de
+-- Stability   :  experimental
+-- Portability :  GHC-only
+--
+-- The real time clock.
+
 module STM32.RTC
 where
 
@@ -34,8 +46,8 @@
   setCounter $ t + offset
 
 
--- setup the batterie powered real-time-clock
--- requieres backup battery and Low speed external crystal
+-- | Setup the batterie powered real-time-clock.
+-- The board should have a backup battery and a low speed external crystal.
 setupLSE_RTC :: Word32 -> MI ()
 setupLSE_RTC epoch = do
   RCC.peripheralClockOn BKP
diff --git a/src/STM32/SPI.hs b/src/STM32/SPI.hs
--- a/src/STM32/SPI.hs
+++ b/src/STM32/SPI.hs
@@ -8,7 +8,7 @@
 -- Stability   :  experimental
 -- Portability :  GHC-only
 -- 
--- The SPI periveral
+-- The SPI peripheral.
 
 {-# LANGUAGE OverloadedStrings #-}
 module STM32.SPI
diff --git a/src/STM32/USART.hs b/src/STM32/USART.hs
--- a/src/STM32/USART.hs
+++ b/src/STM32/USART.hs
@@ -161,7 +161,7 @@
   RCC.peripheralClockOn $ fst _UartRXWire
   RCC.peripheralClockOn AFIO
 
-  GPIO.pinMode _UartTXWire (AlternateOutPushPull Mhz_2)
+  GPIO.pinMode _UartTXWire (AlternateOutPushPull MHz_2)
   GPIO.pinMode _UartRXWire InputFloating
 
   STM32.USART.enable _UartPeripheral