I’ve found that the Nano will work using either “AVR ISP” or “Arduino ISP” selected under Tools->Programmer.<\/p>\n
Serial Ports<\/h4>\n
The Uno only has one serial port. It is possible to simulate additional serial ports in software, though latency issues can make this impractical.<\/p>\n
The Mega has 4 serial ports. One of those (Port 0) is shared with the on-board ISP circuit. So if you have an external device (such as a MAX232 converting TX0 and RX0 from TTL to EIA levels), you MUST disconnect the external RX0 connection before attempting to “upload” a Sketch to the Mega. If you fail to do this, the upload operation will fail.<\/p>\n
The Mega appears as a regular USB-to-RS232 COM Port in Windows 8. So you can connect to this using PuTTY (or similar terminal emulation program).<\/p>\n
The Arduino IDE also has a built-in Serial Port Monitor that communicates with the Mega’s Serial Port 0. This works really well for sending debugging information from your Sketch to the outside world. However, it is NOT ANSI-compatible, so if you try to send formatting commands (such as those used by the DEC VT100 terminal) to Serial Port 0, they will not be interpreted and acted on by the Serial Port Monitor.<\/p>\n
Manually configuring the timers and PWM<\/h4>\n
You can manually configure timers and PWM outputs without the need for any libraries.<\/p>\n
Here are some links I found helpful when coding an LTC output (switchable 50Hz or 60Hz 50% duty cycle):<\/p>\n
Adafruit’s Timer Interrupts webpage<\/a><\/p>\n Arduino 101: Timers and Interrupts<\/a><\/p>\n Advanced Arduino: direct use of ATmega counter\/timers<\/a><\/p>\n Microcontroller tutorial series: AVR and Arduino timer interrupts<\/a><\/p>\n Secrets of Arduino PWM<\/a><\/p>\n AVR Timers \u2013 CTC Mode<\/a><\/p>\n<\/div>\n Here are a few things about the Arduino that are not intuitive:<\/p>\n I purchased this LCD from Jaycar in June 2017 for about $30.<\/p>\n As a novice LCD experimenter, this seems to be a nice product. It offers:<\/p>\n Jaycar’s webpage for this product is here<\/a>.<\/p>\n The LCD is driven by an 8-bit parallel interface (plus 5 control lines), and the Micro SD card uses the Arduino’s SPI interface. Having a parallel interface to the LCD makes it relatively quick, but one downside of this product is that it uses virtually all available I\/O pins on the Arduino Uno. Only 3 or 4 pins are left for you to use for other purposes. <\/p>\n The LCD will apparently also work on an Arduino Mega (which will of course provide many spare I\/O pins). However, be aware that the Micro SD card reader will not work on the Arduino Mega, as the SPI pins are on a different connector. I have read that you can re-configure the Arduino IDE so that the Arduino Mega instead uses a “SOFT SPI” option, but I haven’t tried this yet.<\/p>\n It seems this product is in fact a re-badged version of the “mcufriend” product that is very common (and very cheap) on eBay. <\/p>\n Both the Duinotech and mcufriend products seem to be derived from Version 1 of the Adafruit 2.8″ TFT LCD (Adafruit Product #376)<\/a>. Adafruit’s Product 376 has since been discontinued by Adafruit and replaced with 2 improved 2.8″ TFT LCD products, each of which now use an SPI interface instead to drive the LCD controller. One of these V2 products uses resistive touch (Product 1651)<\/a>, and the other one uses capacitive touch (Product 1947)<\/a>.<\/p>\n Adafruit provided libraries for Product 376 (see the links as the bottom of Adafruit’s product page). However, the Adafruit TFT LCD library was written to support the controllers used in Product 376 (being ILI9325, ILI9328 or HX8347). The Duinotech\/mcufriend product instead uses an ST7781 controller<\/strong> (which reports an ID number of 7783). This controller is NOT compatible with Adafruit’s stock TFT LCD library and is also NOT compatible with the stock Adafruit example TFT LCD programs that are included in the library subdirectory.<\/p>\n So you must use the Duinotech\/mcufriend libraries AND their associated example programs instead.<\/p>\n There are several web posts that provide modified TFTLCD libraries that are supposed to work with this board. None of them worked for me.<\/p>\n However the good news is that I was able to get this board to work using the libraries and example sketches that were provided on the Jaycar product page (I just didn’t look closely enough there to notice them at first).<\/p>\n Here are the files from Jaycar’s product page:<\/p>\n Datasheet<\/a><\/p>\n Software (libraries and example code)<\/a><\/p>\n<\/div>\n [DESCRIBE WHAT IS DIFFERENT IN THE JAYCAR-SUPPLIED LIBRARIES]<\/p>\n NOTE: The example sketches that you want to use are those in the “XC4630v2” directory of the above ZIP file.<\/p>\n [INSERT A LIST OF THOSE EXAMPLES AND THEIR DESCRIPTION]<\/p>\n There are more examples in the individual library directories. The examples in “Adafruit_TFTLCD” and “TouchScreen” directories don’t work at all. The ones in the “MCUFriend_kbv” directory mostly work (see descriptions below).<\/p>\n Here is a brief description of the example sketches in the libraries\/MCUFRIEND_kbv\/examples directory:<\/p>\n NOTE: Adafruit’s compatibility page<\/a> says that the 2.8″ TFT Touch Shield can be used on the Mega by editing the file C:\\Program Files (x86)\\Arduino\\libraries\\SD\\src\\utility. You just change the line that says “#define MEGA_SOFT_SPI 0” to “#define MEGA_SOFT_SPI 1”. I haven’t tried this yet.<\/p>\n On the Uno, all I\/O pins are capable of generating a “pin change interrupt”. However, they don’t each have separate interrupt vectors (24 pins share 3 interrupt vectors). <\/p>\n On the Mega, the pins capable of generating a “pin change interrupt” are those designated with the name “PCINTx”, where x is 0 to 23. Note however that PCINT11 to PCINT15 do not have a physical connection to any of the headers on the Mega board. I’m working with PCINT0, which is the “SS” pin on the Mega (Mega Pin 53, PB0).<\/p>\n These are the resources that I used to get pin change interrupts working for my QBUS Front Panel project:<\/p>\n EXTERNAL INTERRUPTS ON THE ATmega168\/328<\/a><\/p>\n Arduino Pin Change Interrupts<\/a><\/p>\n AVR1200: Using External Interrupts for megaAVR Devices<\/a><\/p>\n<\/div>\n Good page on technique for conditional compiling based on board type -> https:\/\/arduino.stackexchange.com\/questions\/21137\/arduino-how-to-get-the-board-type-in-code<\/a><\/p>\n Information about Arduino boards:<\/p>\n Good introduction to the Arduino Mega<\/a><\/p>\n Good introduction to Arduino Mega 2560<\/a><\/p>\n Arduino Mega Schematic<\/a><\/p>\n Good picture of the pinouts on the Arduino Uno board<\/a><\/p>\n Good picture of the pinouts on the Mega board<\/a><\/p>\n Nice dimensioned drawings of the UNO and Mega<\/a><\/p>\nThings to be aware of<\/h4>\n
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Duinotech 2.8″ TFT LCD with resistive touchscreen<\/h4>\n
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\ntestcard_kbv: Shows a picture similar to a TV test pattern.<\/li>\nPin Change Interrupts<\/h4>\n
Miscellaneous Programming Issues<\/h4>\n
Links<\/h4>\n