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• Step 2

  Phil • 10/19/2025 at 07:24 • 0 comments

  I replaced the cooked Mega8 with a arduino compatible ATMEGA328PU and soldered in a 16MHz crystal. I also replaced the HT1632C ICs I purchased on ebay. I soldered in the DS18B20 and DS1302S ICs and located a 32KHz crystal amongst my spare crystals parts drawer. 

  First thing was to test the Arduino and make sure I could flash the boot loader to it. I then realised since I was using the ISP method to program the MEGA328 I didn't need the boot loader.

  Next was the RTC, I found a basic sketch that programmed the RTC with the compile time and then endlessly outputed the time via the serial port.

  After that was the DS18B20, same this again, I found a simple sketch that read the temperature and sent it out the serial port.

  The last thing was the HT1632C IC. The required a more complicated sketch which I found and this was when I realised the displays where at a odd rotation (to me anyway). The 8x8 matrix displays are layed out so that 1 to 4 is from the Right to the Left and the displays are rotated 90 degrees clockwise.

  The Arduino libraries that have been writen both others are pretty cool and do all the fancy graphics, however I wanted to start simple with just turning on and off pixels and creating my own characters. 

• Step 1.

  Phil • 10/18/2025 at 07:10 • 0 comments

  Flipping the board on its face reveals two main chips. The ATMEGA8 and the HT1632C. The unpopulated components, one of which had a silk screen identifier (DS18B20) and the other was a give away due to the footprint for a tuning fork crystal. Which RTC IC was now the mystery, so out came the trusty multimeter and datasheets.

  The IC (8 pin SOIC) was either going to be a DS1307 or a DS1302. The location of the crystal connections is different for both ICs so the DS1302 was assumed the correct one after a check of the datasheets. The multimeter then told me which pins of the ATMEGA IC they where connected to. 

  My attention them moved to figuring out where the HT1632C pins went and recording them. After that was established the 10pin IDC header was the next stop.

  The IDC header had the pins for programming with an AVR ISP MKII as well as serial. I wanted to use the Arduino IDE however the header didn't have the DTR pin for reset the ATMEGA. So I choose to use the AVR ISP MKII and was able to use the "Upload Via Programmer" function.
  
  
  

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