08M2 Another LCD Clock

Pete Shep

New member
This was more a "Can I do it?" than a proper project as I'm rubbish at boxes and cases.
I had previously done something similar with an Arduino (with additional LED array display and "beep the hours and quarters"), but that used "librarys" which takes a lot of the fun out of it.

The circuit consists of:
I2C interface board based on a PCF8574T - (Philips Remote 8-bit I/O expander for I2C-bus) - seems original data sheet may have been dated 1994!
The chip effectively adds 8 i/o pins, controlled by I2C.

A DS3231 I2C RTC assembly with an included AT24C32 RAM chip - didn't have a use for that - maybe Data Logger???
Needs a bigger PICAXE for more inputs

The LCD interface and RTC board are from AMAZON or similar.

Plus an "Arduino style Multiple buttons to 1 Analog input"' interface board - saw it first on Arduino LCD & Keypad Shield
I re-vamped the resistor values and switches - still not sure what the best set up is for this....
Buttons are:
Up - increase value
Down - Decrease value
Select - "That's the one I want"
Back - "Go back without changing anything"

LCD software influenced (nicked!) from Hippy. Ta Hippy!
PLUS see: (I'm sure it is available at other places)
"How to Use Intelligent LCDs" by Julyan Ilett from Everyday Practical Electronics 1997
I believe this is the HD44780 "Bible".
Clk Cct Diag & Comps.png