Updates the documentation for the new version

Author: hadoopmarc

README.md

@@ -69,7 +69,7 @@ In this image the yellow line represents the light throughput of the LCD shutter
 
 ![](doc/image/Arduino@H-bridge-LED.png)
 
-Again the light throughput against the GPS Pulse Per Second signal, but now for the optimized design with Neo-M8N, an Arduino and an H-bridge. Now, the GPS pulse has a duration of 100 ms and the duty cycle of the driver pulses is 50%, which gives the LCD-shutter more time to open than in the earlier image for the reference design.
+Again the light throughput against the GPS Pulse Per Second signal, but now for the optimized design with a Neo-M8N GPS module, an Arduino Nano and an H-bridge. Now, the GPS pulse has a duration of 100 ms and the duty cycle of the driver pulses is 50%, which gives the LCD-shutter more time to open than in the earlier image for the reference design.
 
 ![](doc/image/Arduino-PB7-vs-signal-F.png)
 
@@ -79,6 +79,10 @@ This picture looks boring, but its significance is high. It displays the referen
 
 This picture is a more attractive-looking variation on the picture above, again combining measurements from two independently operating setups. Here, signal F from the reference design (white line) is combined with the light throughput of the LCD shutter driven by the optimized design (yellow line). Also, here the opening and closing instances of the LCD-shutter nicely coincide with the falling and rising edges of signal F. Note that the measurements in the last two images were made with the electronic circuits built on a printed circuit board, while previous more noisy images were from circuits built on a breadboard. Also, a different phototransistor and LCD-shutter were used, explaining the slightly different light throughput curve, compared to the earlier images.
 
+![](doc/image/Arduino@H-bridge-LED-25percent.png)
+
+Starting from version 0.2.0 the electrical shut percentage can be configured to compensate for LCD shutters that fail to reopen fast enough to truthfully follow the electrical signals. In this oscilloscope screenshot a shut percentage of 25% is applied to a cheap LCD shutter, resulting in an open/closed ratio of roughly 50/50. White line is the GPS signal.
+
 ## Phase measurements in the optimized design
 
 Apart from validation measurements of the output signals of the electronic circuits, it is also possible to use internal measurements from the microcontroller as a form of validation. The controlling software generates the pulses using timer interrupts. The timer period is chosen such that the end of a pulse train occurs at a phase difference Δt just before the ideal time instance required by the nanosecond precision GPS time. For an Arduino Nano microcontroller the timer has a limited resolution and as a result Δt has a stable value between 0 and 128 microseconds. How to monitor this phase difference and phase stability is described [here](./doc/arduino-programming.md).

doc/arduino-programming.md

@@ -12,19 +12,20 @@ Most likely you use Microsoft Windows and you can simply install the Arduino IDE
 
 The latest software for the GPS-controlled LCD shutter driver can be downloaded from:
 
-[https://github.com/hadoopmarc/gps-controlled-lcd-shutter/archive/refs/heads/main.zip](https://github.com/hadoopmarc/gps-controlled-lcd-shutter/archive/refs/heads/main.zip)
+[https://github.com/hadoopmarc/gps-controlled-lcd-shutter/tags](https://github.com/hadoopmarc/gps-controlled-lcd-shutter/tags)
 
-Extract the archive at some place where it can easily be found back. Of course, if you know how to use git and want to contribute to the repository, you can git clone the repository instead of donwloading the archive.
+Select the version you need, supposedly the latest version, download the source code archive and extract it at some place where it can easily be found back. Of course, if you know how to use git and want to contribute to the repository, you can git clone the repository instead of downloading the archive.
 
 ## Programming the Arduino
 
 Programming the Arduino Nano should now be so simple as:
 
 1. connect the Arduino to your PC/laptop using a USB-cable
-2. open the local file 'gps-controlled-lcd-shutter/arduino/waveform-h-bridge/waveform-h-bridge.ino' with the Arduino IDE. This will open three files in separate tabs. The file gps_shutter_control.cpp contains the actual program. The two other files prepare the Arduino for later extensions.
-3. select the Arduino Nano from the "Tools / Board / Arduino AVR boards" menu option
-4. select the right COM-port from the "Tools / Port" menu option (if no COM port is marked as Arduino Nano, disconnect and reconnect the Arduino to discover the right COM port)
-5. push the "Upload ->" button in the taskbar. If the compilation fails, please contact the repository owner. If the upload fails, disconnect and reconnect the Arduino and try again.
+1. open the local file 'gps-controlled-lcd-shutter/arduino/waveform-h-bridge/waveform-h-bridge.ino' with the Arduino IDE. This will open three files in separate tabs. The file gps_shutter_control.cpp contains the actual program. The two other files prepare the Arduino for later extensions.
+1. in the file 'waveform-h-bridge.ino' manually edit the required SHUT_PERCENTAGE for the connected LCD-shutter system
+1. select the Arduino Nano from the "Tools / Board / Arduino AVR boards" menu option
+1. select the right COM-port from the "Tools / Port" menu option (if no COM port is marked as Arduino Nano, disconnect and reconnect the Arduino to discover the right COM port)
+1. push the "Upload ->" button in the taskbar. If the compilation fails, please contact the repository owner. If the upload fails, disconnect and reconnect the Arduino and try again.
 
 The microcontroller on an Arduino board may have so-called [lock bits](https://microchip.my.site.com/s/article/Use-of-Lock-Bits-in-AVR-devices)or [fuses](https://circuitdigest.com/microcontroller-projects/understanding-fuse-bits-in-atmega328p-to-enhance-arduino-programming-skills) set such that it cannot be programmed with the Arduino IDE anymore. The lockbits can be reset by following the [Arduino bootloader burning procedure](https://docs.arduino.cc/built-in-examples/arduino-isp/ArduinoISP/#recap-burn-the-bootloader-in-8-steps). Resetting fuses requires 12V programming with a [more convoluted setup](https://www.instructables.com/HV-Rescue-Simple/) and is totally impractical for an Arduino Nano with a soldered SMD microcontroller.