The Sinclair QL Forum

Here is what I could salvage. Not sure I can explain a lot. I did it to test breadboard for the Iridium Next Satellite Constellation 15 years ago.


Many thanks François

Will take a look thru

Many thanks
Tony


FYI, the I2C minerva was used in conjunction with the power board from TF ...

FrancoisLanciault wrote: Fri May 23, 2025 5:57 pm Here is what I could salvage. Not sure I can explain a lot. I did it to test breadboard for the Iridium Next Satellite Constellation 15 years ago.

Many thanks François

Will take a look thru

Many thanks
Tony

A slight code mod to make use of all 4 rows (note that the order of the text is line 1, line 3, line 2, line 4)

The I2c address of the PCF8574 is defaulted to either $27 (TI make) or $3f (NXP make) but there are 3 jumpers that can be soldered to change the address if needed (so you can have multiple LCD's on same I2c BUS)

Hi,

The VBAT is not part of the I2C Interface, but Voltage BATtery

I have ordered a similiar LCD, which has anArchino s8oldered to the back of the LCD, where the I2C Interface is connected.

I assume yhe I2C Address is setup in the Arduino.

I will try it on a Q68 I2C, which can use 5v I2C ...

With regards to attaching the LCD to a MK2 Remake the vBat (not used for LCD) is the pin on J2 nearest the crystal

The LCD seems happy to draw it's power from the 5v pin

Nice work! The software looks relatively straightforward if you can program it from BASIC like that.


I kept looking at the code and couldn't understand why it needed to send 4 times for each byte to display (instead of 2 x 4bits), so have edited out the send at lines 100/120 & deleted line 220 ...

Am happy to report I've finally got the LCD working with the I2c interface, so definitely working on the mk2 remake


IMG_4779.jpeg



Hi Tony,

What is the make of the LCD?


Hi Derek,

There's no identifying marks on it that I can find, but the eBay seller has re-listed it https://www.ebay ...

Am happy to report I've finally got the LCD working with the I2c interface, so definitely working on the mk2 remake


IMG_4779.jpeg


It's very simple test code (wasn't that simple to get it working though as it turned out, but that was down to my lack of understanding) but credit needs to go to ...

FrancoisLanciault wrote: Mon May 19, 2025 3:48 pm
My Minerva mk2 died a few years ago. but I think I still have some code on my old ROMdisk. Let me check.

Hi François,

Have managed to get the LCD working now, but if you do manage to find any sample code sometime that would be great please

Many thanks
Tony