Finishes the PWM driver for the STM32

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4206 42af7a65-404d-4744-a932-0658087f49c3

configs/stm3240g-eval/README.txt

@@ -14,6 +14,7 @@ Contents
   - STM3240G-EVAL-specific Configuration Options
   - LEDs
   - Ethernet
+  - PWM
   - Configurations
 
 Development Environment
@@ -203,6 +204,21 @@ events as follows:
     on a small proportion of the time.
 *** LED2 may also flicker normally if signals are processed.
 
+PWM
+===
+
+The STM3240G-Eval has no real on-board PWM devices, but the board can be configured to output
+a pulse train using TIM4 CH2.  This pin is used by FSMC is connect to CN5 just for this
+purpose:
+
+  PD13 FSMC_A18 / MC_TIM4_CH2 pin 33 (EnB)
+
+FSMC must be disabled in this case!  PD13 is available at:
+
+  Daughterboard Extension Connector, CN3, pin 32 - available
+  TFT LCD Connector, CN19, pin 17 -- not available without removing the LCD.
+  Motor Control Connector CN15, pin 33 -- no available unless to connect SB14.
+
 STM3240G-EVAL-specific Configuration Options
 ============================================