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--- electronics:thermoprinter [2017/11/22 06:18] – dmmedia
+++ electronics:thermoprinter [2020/04/02 20:33] (current) – [02.04.2020] dmmedia
@@ Line 278: / Line 278: @@
   * Tested both HC-05 and SPP-C modules. HC-05 modules need to be powered on in special sequence to boot into AT command mode, while SPP-C modules are always in AT mode, while not connected to other Bluetooth device. Both modules do not require hardware flow control. Many android software applications support traditional Bluetooth serial communication.
   * Firmware code is mostly ported from AVR to STM32 platform and unneeded functionality removed. At the moment ADC code left partially ported.
+==== 08.03.2018 ====
+  * Counting printable bits to optimize the number of simultaneously driven 64-bit blocks turned out to be a combinatorial task or [[https://en.wikipedia.org/wiki/Partition_problem|Partition problem]]. More specifically a [[https://en.wikipedia.org/wiki/Bin_packing_problem|Bin packing problem]]. Generally speaking, the resulting count of sums of simultaneously driven blocks will be not more than optimal count plus 2 if I would use First fit decreasing or Best fit decreasing algorithms.
+  * Counting bits themselves turned to be another well-known problem named [[https://en.wikipedia.org/wiki/Hamming_weight|Hamming weight]]. Need to check whether STM32 has any special support for bit counting.
+==== 02.04.2020 ====
+  * Thought that porting Marlin 3D printer firmware was bad idea, since the functionality is totally different and Marlin implementation is not brilliant. Will start from scratch and implement stepper motor advance on user button press and hold. Motor will advance with the lowest speed described in the thermal head manual. Next step will add accelleration and deceleration.