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Board: Jiminy atmega256rfr2

Jose Alamos edited this page Aug 9, 2018 · 19 revisions

WARNING: This entry will be deprecated. All content has been moved to


The Jiminy board is a development of the Chair of Integrated Analog Circuits and RF Systems (IAS) of the RWTH Aachen University. We started the project by porting Riot OS to the board. As there where severe limitations we designed the Jiminy board which has the the ATmega256rfr2 MCU as common feature.

It is Arduino like and features USB programming. The Bootloader is a fork of the Arduino Bootloader with added functionality for internal clock calibration and automatic baud rate detection.

The Jiminy is design as a core board featuring a MCU, RF-transceiver, battery charger and power path management IC, a fuel gauge, an adjustable power supply between 1.8V to 3.3V (100mV Steps) and an RGB LED. All unused Pins are connected to pin headers.

An USB C connector is used to connect to the computer or the charger. As USB C supports up to 3 ampere the board was designed in regard of fast charging and when connected to the grid or usage of big batteries high current supply capability for the shield.

The shields can be powered either directly from the Charger/battery or from the adjustable converter, the converter supply pin can be enabled or disabled by the application. By connecting shields to the core Jiminy board, a multitude of wireless applications can be created.

A first shield for temperature, humidity and soil moisture measurement is also developed at the IAS.

If there is demand for devices please contact the author of this page for more details.




The jiminy board has following ICs and features.

Features Details Datasheet
USB2Serial ATmega16U2, High-performance, low-power AVR 8-Bit Advanced RISC Architecture Link
MCU ATmega256, AVR 8-Bit Advanced RISC Architecture Link
Transceiver High performance RF-CMOS 2.4 GHz radio transceiver targeted for IEEE802.15.4, ZigBee, IPv6 / 6LoWPAN, RF4CE, SP100, WirelessHART and ISM applications above
Li-ion Charger and Power Path bq24298 , 3A Single Cell USB Charger With Power Path Management Link
Fuel Gauge LC709203F, Fuel Gauge for a single lithium ion battery which provides accurate RSOC information even under unstable conditions (e.g. changes of battery temperature, loading, aging and self-discharge) Link
AC Converter TPS6274x, Output voltage selectable within a range from 1.8V to 3.3V in 100mV steps, output currents up to 300mA Link
RGB LED Cree LED, hardware PWM controlled Link

MCU Details

MCU ATmega256RFR2
Family ATmega
Vendor Atmel
Package QFN/MLF
Flash 256Kb
Core Frequency 8MHz (16MHz no power save mode)
Oscillators 32.768 kHz & 16 MHz
Timers 6 ( 2x8bit & 4x16bit )
Analog Comparator 1
ADCs 1x 15 channel 6 to 12-bit
SPIs 3 (1 SPI & 2 USART SPI)
I2Cs 1 (called TWI)
Vcc 1.8V - 3.6V
Datasheet / Reference Manual Datasheet and Reference Manual
Board Manual

Implementation Status

Is an ongoing process ...

Jimini Core

Driver Status Comment
Timers OK
PWM OK only PWM_left implemented yet
Comparator OK
Module Status Comment
Stdio OK Output to USB Bridge, used as Terminal
xTimer OK
Power Path OK
Fuel Gauge OK
RF core Work in progress
CoAP Status Comment
Battery ok only RSOC so far

Jimini Plant Sensor Shield

Module Status Comment
Soil moisture OK
CoAP Status Comment
Temperature ok
Humidity ok
Soil moisture ok when reqeusted the first time the returned value is wrong, after that the correct value is returned

Flashing RIOT

Flashing RIOT on the Jiminy is quite straight forward, just connect your Jiminy using the USB port to your host computer and type:

make flash BOARD=jiminy-mega256rfr2

This should take care of everything!

RIOT's Makefile are configured to flash the jiminy using AVRDUDE. The bootloader automatically matches to the configured baud rate which is set for AVRDUDE. Rates of up to 500kBaud can be used.

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