Project home: Original repository at:

Michael Buesch 7615b314b0 Optimize HSL calculation for code size 19 hours ago
firmware 7615b314b0 Optimize HSL calculation for code size 19 hours ago
remote 0916d709d7 remote: If only one SP is passed, apply it to all. 5 days ago
schematics-atmega 9c1ca57e47 Minor updates to documentation 1 month ago
schematics-attiny 52a5dfb089 schematics: Add pull down at output stages 2 months ago
.gitignore db6bc0b502 Add README 5 months ago
COPYING c4898dd41d Initial commit 2 years ago
README.rst ed1c645c85 Add bootloader support 1 week ago
battery_drop_curve.ods 759a5ae668 Move ods 5 months ago
brightness_curve.ods 759a5ae668 Move ods 5 months ago 4b2782791b Bump version 5 days ago
version.txt 4b2782791b Bump version 5 days ago


Simple PWM controller

` `_

Simplepwm is a small PWM brightness controller for LED lamps.


Simplepwm supports the following microcontrollers. Not all features are supported on all microcontrollers. See the table for details.

============================ =========== ============ ========= ========= ========= =========
.. ATMega-328P ATMega-88(P) ATTiny-85 ATTiny-45 ATTiny-25 ATTiny-13
============================ =========== ============ ========= ========= ========= =========
Number of analog pot. inputs 3 3 1 1 1 1
Number of PWM outputs 3 3 1 1 1 1
Power saving x x x
Battery voltage monitoring x x x
HSL color model x x
Remote control via UART x x
Settings in EEPROM x x
Debugging via UART x x
Firmware update via UART x x
============================ =========== ============ ========= ========= ========= =========

Hardware schematics

Schematics for ATMega based setups: `schematics-atmega/simplepwm-atmega.pdf `_

Schematics for ATTiny based setups: `schematics-attiny/simplepwm-attiny.pdf `_

Prebuilt firmware images

The release archives of simplepwm contain prebuilt `.hex` files for all supported microcontrollers in the `hex` directory. These hex files can be flashed directly to the microcontroller with a any tool of your choice (e.g. Atmel Studio or avrdude).

The corresponding fuse settings can be found in the file `fuses.txt` in the same directory.

Building the firmware

The firmware build needs the following tool chain:

* Unix-like operating system
* GNU make
* AVR Binutils
* avrdude

Run the following commands to build the firmware:

.. code:: sh

cd firmware
make DEV=t85

Please specify the target microcontroller using the DEV variable as shown above.

Valid values are:

=============== ===========
Microcontroller make option
=============== ===========
ATTiny 13 `DEV=t13`
ATTiny 25 `DEV=t25`
ATTiny 45 `DEV=t45`
ATTiny 85 `DEV=t85`
ATMega 88 `DEV=m88`
ATMega 88P `DEV=m88p`
ATMega 328P `DEV=m328p`
=============== ===========

Additional build options that can be passed to `make`:

=============== ====== ============== ================================================================
make option values default description
=============== ====== ============== ================================================================
CONF_PWMLIM 1-100 100 Limit the maximum PWM duty cycle to this percentage.
CONF_PWMINVERT 0-1 0 Invert the PWM output signal(s).
CONF_LOWSPFACT float 1.0 Correction factor for lower range PWM setpoint.
CONF_ADCINVERT 0-1 0 Invert the ADC input signal(s).
CONF_ADCHSL 0-1 depends on DEV Interpret the ADC input signals as HSL setpoints instead of RGB.
FEAT_HIGHRES 0-1 depends on DEV Higher resolution in very low PWM setpoint range.
FEAT_BATTERY 0-1 depends on DEV Battery voltage monitoring
FEAT_POWERSAVE 0-1 depends on DEV Power saving / deep sleep
FEAT_REMOTE 0-1 depends on DEV Remote control via UART
FEAT_EEPROM 0-1 depends on DEV Store settings to EEPROM
FEAT_BOOT 0-1 depends on DEV Enable bootloader and firmware updating via UART.
=============== ====== ============== ================================================================

Flashing the firmware after build

Run the following commands to flash the firmware to the target microcontroller:

.. code:: sh

cd firmware
make DEV=t85 print_fuses
make DEV=t85 write_fuses
make DEV=t85 write_mem

Or alternatively use any other of the available AVR flashing tools to program the .hex file and fuses.


Copyright (c) 2018-2020 Michael Buesch

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.