Pinouts
The Reflowduino's pinout is identical to the Arduino Leonardo with the main exception that the Reflowduino operates on 3.3V logic, NOT 5V! Also, there are some added features on the board that are worth noting. Below is a general Reflowduino pinout diagram. The only difference between the Reflowduino Basic and Reflowduino Pro is the solid-state relay on the Pro version.
The Reflowduino can be powered via micro USB, by a LiPo battery, or both (during which the battery will charge)! Since the default battery charging current is 250mA, the LiPo battery should be at least 250mAH for safe charging. Please note that the Reflowduino does not accept external voltages
- GND - Common ground for all logic and power
- VBAT - LiPo battery voltage from the JST battery connector
- 3.3V - 3.3V output from the regulator which can output 600mA
- 5V - This micro USB voltage will only be present when the board is plugged in and is NOT a regulated 5V by default! This voltage is protected by a resettable PTC fuse that trips if the board tries to draw more than 750mA via USB, like during an electrical short or something eating up too much power! If this happens, fix the problem (remove the short) and the fuse will reset back to normal!
The Reflowduino's ATmega32u4 runs on 3.3V logic, so make sure not to exceed 3.3V on any logic pin! Pins that are labeled with a "~" are capable of PWM (analog output).
- D0 - Digital / Serial RX
- D1 - Digital / Serial TX
- D2 - Digital / SDA
- D3 - Digital / PWM / SCL
- D4 - Digital
- D5 - Digital / PWM / Controls piezo buzzer
- D6 - Digital / PWM
- D7 - Digital / Controls solid-state relay
- D8 - Digital / MAX31855 chip select pin
- D9 - Digital / PWM / Bluetooth RX
- D10 - Digital / PWM / Bluetooth TX
- D11 - Digital / PWM
- D12 - Digital
- D13 - Digital / PWM / Red "IO" LED
- A0 through A5 - These are digital pins but with analog input capability
- SCK/MISO/MOSI - Hardware SPI pins used to communicate with MAX31855 and to program the ATmega32u4
- RESET - This pin will reset both ATmega32u4 and the Bluetooth module when momentarily connected to GND and is the same as pressing the RESET button on the board
- AREF - Analog reference pin for the ATmega32u4's ADC. This voltage must be within 0 to 3.3V!
There are several user-configurable solder jumpers and traces on the Reflowduino which are listed below:
- Charge Current - Bridge this solder jumper with solder to set the LiPo charging current to 500mA instead of 250mA (default). However, please note that your LiPo should be at least 500mAH capacity if you charge it at 500mA.
- Buzzer - Cut in between the two pads to disconnect digital pin 5 from the piezo buzzer. If you later change your mind it's not the end of the world! Just bridge the jumper with solder if you decide to reconnect the buzzer
- 3V3 - Bridge this jumper with solder to connect the pin directly under the jumper to 3.3V. On the Arduino this is the "VIN" pin but since the Reflowduino doesn't accept input voltages other than the LiPo battery and micro USB this pin is left floating by default
- Relay Voltage Select - Cut the connection in between the middle and right pads with a razor blade and and bridge the left and middle pads with solder to select the USB voltage (around 5V) instead of the default 3.3V to control the relay. This is especially useful for Reflowduino Basic boards where the relay isn't already provided and a different relay requires a higher control voltage
- Power ON - This green LED (labeled "ON" on the board) is on whenever the board is powered, whether via micro USB or LiPo battery (or both). If you really want to save energy on battery power you can de-solder the LED but be careful!
- User LED - This red LED (labeled "IO") is connected to digital pin 13 and also pulses after the reset button is pressed to indicate that the bootloader is active
- Charging Done - This green LED (labeled "DONE") turns on when a LiPo battery is plugged in and fully charged
- Bluetooth Connection - This blue LED (labeled "BT") flashes on/off when the Bluetooth module is not connected. The LED turns solid when a connection is made
- Screw Terminal - The screw terminal is for the K-type thermocouple. If you peel back the outer insulation on the thermocouple wire slightly you should see the color of each wire (yellow or red). Secure these wires in the screw terminal according to the polarity shown on the board (red on top, yellow on the bottom)
- Battery Connector - Next to the screw terminal is a 2mm JST-PH for the LiPo battery. The Reflowduino will work with standard LiPo batteries with JST connectors like from Sparkfun or Adafruit. If you order batteries from other suppliers always check to make sure the polarity is correct. The positive wire should be on the left side and negative on the right when plugged into the JST connector.
- Relay Control Pads - On the right side of the board are two pads labeled "RLY+" and "RLY-". These are the control pins of the solid state relay on the Reflowduino Pro. If you have a Reflowduino Basic, these pins can be connected to the control pins of a relay with the proper polarity.
- Relay Output Pads - On the Reflowduino Pro there are also two pads for soldering wires to the output of the solid-state relay! Note that in the latest version of Reflowduino the pads are physically separated by a cutout in the PCB for greater safety.
