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Good afternoon Hippy. I attach a zip of the whole directory of my program - this includes the subroutines and definitions which are included in the slot sections, as needed. I was hoping that you might try to reproduce the problem I see, by using all of my files to program a 28X2. I'm using a...

The attach system wont let me select the definitions file and the subroutines file which are both included in the slot # files. How do I overcome that ?

Here are all my files - attached for anyone with insomnia. This feels risky, as it probably opens up more questions than it answers, and the code is nowhere near a polished thing. But it does work in the broad sense of running my solar and hot water system. I'm adding new functions, such as the...

Hi Hippy see my last post - no, the interrupt routine doesn’t alter ptr, or w3, or any of its components. I guess my logic is almost the reverse of yours - by reducing the problem to a tiny section of code with a go / nogo result - however impossible, that must be the problem! This is entirely...

This is probably a very dumb question, but the suggestion of interrupt being the culprit does raise a question - I'm using all 4 slots of the 28X2 - slot 0 for initialisation, then slots 1, 2, 3 in rotation - the main loop skips between the 3, calling subroutines partitioned into each slot. I...

Hi Hippy & Buzby Thanks for the clarification of the effect of an instruction such as "w3 = @ptr". I understand and accept what you say. HOWEVER, I think it would be of some benefit to other users to have the action of the @ptr instruction clarified for this case. To me, assuming that a word...

Hi Hippy Yes, I agree with almost all of that. But I also realised that there's even more strangeness here. The little snippet of code is to be able to edit the values stored for the PICAXE to work as a heating system programmer, with blocks of start and end times, with a temperature in...

Hi Hippy "Not sure why your 'doesn't work' version doesn't because the Scratchpad stuff worked when I tested it in the simulator and on an actual 28X2 I suspect the issue is with your magic values and your incrementing or decrementing and display of the values" The point is that I've been very...

Hi Hippy Thanks for that very comprehensive info. But in my code samples - what exactly have I done wrong in take #14 which is right in take #15 ?

Hi All I've just spent a while trying to work out why some code didn't work as expected. The code copies a 16-bit data value (a temperature value with lsn being 1/16ths of degree), from a block in scratchpad, then allows the value to be increased or decreased before placing back into...

Hi Again guys. I'm pleased to say I've got the display working. I spent quite a while understanding WHY the interface has to be 4-bit, and checking all of the pins on the HD44780 and the PCF8574A. Using that knowledge, and hints from other places, I found that the "missing" bit 3 from the...

Ah, the formatting of my table didn't survive. Hope you can untangle it...

Hi Again guys. To Flenser - to clarify, I have two PICXAXE28 development boards - one continues to use the 28X1 chip and it's established code, display etc controlling my solar. I've set up connectors so that I can change the new board, with the 28X2, into the operating solar system. But since...

Hi Flenser Thanks for your comments. I've tried using Hippy's code, with the only change being to set my i2c address to $7c. It doesn't appear to work "out of the box". Probably the mapping of the interface chip to the LCD module. But the complication of the 4-bit interface seems to be a lot...

Hi Alan Thanks for that info. I was at a brick wall for quite some time, not knowing if it was a hardware or software problem, but I'm gradually peeling the layers now, with the hints from you and Jeff Haas. I'd worked out the PICAXE version of the i2c address ($7c with address pin A0 held...

The i2c converter is based on a PFC8574AT chip (hence the $3F address), and I assume (but don't know), that the display will be based on the HD44780 standard.

Hi All I've recently bought an unbranded 20x4 LCD display and an unbranded i2c converter, for use with a 28x2 PICAXE project. I already have an AXE033 clock and display, and wanted to add a second display. However it's proving impossible to get any response from the new display. The only thing...