As explained above, pin numbering starts from 0. Hence A0 to A5 are six pins.Īrduino MEGA 2560 boards have sixteen analog input pins, labelled A0 to A15. Because pin numbering starts from 0, there are actually six pins. At first glance A0 to A5 looks like five pins. Arduino Analog Input PinsĪrduino Uno boards have six analog input pins, labelled A0 to A5. The potentiometer varies or changes the voltage on the Arduino analog input pin. Use a potentiometer in this part of the Arduino tutorial for beginners in order to read an analog input with Arduino. In addition, it provides basic information on potentiometers. This article shows different potentiometer symbols used in circuit diagrams. The potentiometer article on this website has more information on potentiometers for beginners. Turn the shaft or screw of the potentiometer to change its resistance. PotentiometerĪ potentiometer is a variable resistor. In addition it is important to know what an Arduino analog input is. To engage in discussion regarding this post, please post on our Community Forum.What is a Potentiometer and Analog Input?īefore reading an analog input with Arduino, it is important to know what a potentiometer is. Spot the common thread in my last few blog posts! I'm planning on using the ATmega32U4 in the emonTx SMT that I'm currently working on. Download it here: įor a simple RFM12B transmission demo/example see: Update: Pull request has been merged, RF12 part of JeeLib Arduino library now has ATmega32U4 support :-). I'm going to send JCW a git pull request to see if these changes can be integrated into the JeeLib library so it should work 'out of the box' in the future. #define SPI_SCK 15 // PB1, pin 9, Digital15 #define SPI_MOSI 16 // PB2, pin 10, Digital16 #define SPI_MISO 14 // PB3, pin 11, Digital14 #define SPI_SS 17 // PB0, pin 8, Digital17 No change to RFM12.cpp is needed, just download the latest version, see update below. To make the JeeLib library work with the Leonardo and RFM12B (hooked up as above) the following needs to be inserted into the RF12.cpp file on line 62 before the else // ATmega168, ATmega328, etc. Arduino 1.0.1 is needed to be compatible with Leonardo. The library needs to be installed in the Arduino library's folder in the usual way. We use the RFM12B driver as part of the JeeLib library from JeeLabs. Now the hardware is complete it's time to tackle the software. Īrduino Leonardo Connections to RFM12B via JeeLabs RFM12B breakout for level shifting to 3.3V See the RFM12B documentation page for general info on RFM12B and details of how to interface with ATmega328. The SEL connection is the same as with the Arduino UNO/ATmega328 goes to digital 10. This has moved from Digital 2 on the Arduino Uno. The IRQ Interrupt connection is made to Digital 3 (INT0). Can anyone explain why this is the case? It's not a big problem, we can use another pin as SS, digital 10 in this case. The SPI SS pin on the Leonardo is not broken out anywhere on the board, strangely it's used for the Rx LED. Unlike on the Arduino Uno These SPI pins are not accessible through any of the digital I/O pins, on om the Leonardo, their only accessible through the ICSP header. Once of the main differences is that the hardware ISP connections are no longer on digital pins 10,11,12 and 13. I made a re-arranged table with the ports re-arranged into function groups. The Arduino port mapping table proves very useful, if a little difficult to interpret. The ATmega 32U4's 'special function' ports such as PWM, IRQ, SPI etc are quite different to the ATmega328. It's been a bit of port mapping nightmare! I've just managed to get an RFM12B hooked up to an Arduino Leonardo.
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