Go to advanced search

by SiriusHardware
Wed Feb 24, 2021 7:04 pm
Forum: Python
Topic: Serial port basics
Replies: 3
Views: 297

Re: Serial port basics

Could someone please explain the parameters '/dev/ttyS0' among other examples I've seen. This one I can help you with. You recall how on DOS / Windows computers serial ports are usually named COM1, COM2, COM3, COM4, and so on? On Linux computers serial ports are called 'tty' ports. The main onboard...
by SiriusHardware
Tue Feb 23, 2021 10:29 pm
Forum: Python
Topic: Write 8-bit raw values to a binary file one at a time?
Replies: 9
Views: 662

Re: Write 8-bit raw values to a binary file one at a time?

What you say is what anyone would logically expect. If I read out and print only the first element of the file created in the example above, the value I should recover (and print) is '0'. But if I print it unmodified (without the ORD conversion) using print (value) it prints an ASCII string, b'\x00'...
by SiriusHardware
Tue Feb 23, 2021 8:36 pm
Forum: Python
Topic: Write 8-bit raw values to a binary file one at a time?
Replies: 9
Views: 662

Re: Write 8-bit raw values to a binary file one at a time?

Thanks again. So this scrap of code (below) does what I actually expect it to. Because this works, can I assume that a byte read from a file in binary read mode is converted to Unicode during the read process, so I therefore have to convert it back to the original byte value using ORD? # Fill a 256-...
by SiriusHardware
Tue Feb 23, 2021 7:46 pm
Forum: Python
Topic: Write 8-bit raw values to a binary file one at a time?
Replies: 9
Views: 662

Re: Write 8-bit raw values to a binary file one at a time?

That's not quite what I am looking for, although I am not sure where it is going wrong. The output I need from the second part of your example (if I understand the first part correctly) is 0 1 2 3 4 5 6... etcetera, all the way up to 255 For the read operation I need to read one byte at a time with ...
by SiriusHardware
Tue Feb 23, 2021 8:58 am
Forum: Python
Topic: Write 8-bit raw values to a binary file one at a time?
Replies: 9
Views: 662

Re: Write 8-bit raw values to a binary file one at a time?

So one further question on this - is there also a way to use the bytes([x]) feature to ensure that when reading bytes FROM a binary file they are just read as raw 8-bit bytes?
by SiriusHardware
Mon Feb 22, 2021 11:13 pm
Forum: Python
Topic: Write 8-bit raw values to a binary file one at a time?
Replies: 9
Views: 662

Re: Write 8-bit raw values to a binary file one at a time?

ghp, thanks for the fast reply. It was the

bytes([x])

syntax I needed. I now have my program writing out one raw 8-bit byte at a time.
by SiriusHardware
Mon Feb 22, 2021 9:50 pm
Forum: Python
Topic: Write 8-bit raw values to a binary file one at a time?
Replies: 9
Views: 662

Write 8-bit raw values to a binary file one at a time?

I'm using Python 3: I have an application where I read an 8-bit parallel value from a hardware device by scanning each of the individual GPIO pins and building them up into an 8-bit value. That part works OK, I can print the received value as decimal or hexadecimal and I see the figure I expect. Wha...
by SiriusHardware
Sat Feb 20, 2021 9:25 pm
Forum: Advanced users
Topic: Maximum current available from +5V on GPIO connector?
Replies: 6
Views: 526

Re: Maximum current available from +5V on GPIO connector?

Davidcoton, thanks, just what I was looking for.
by SiriusHardware
Sat Feb 20, 2021 9:42 am
Forum: Advanced users
Topic: Maximum current available from +5V on GPIO connector?
Replies: 6
Views: 526

Re: Maximum current available from +5V on GPIO connector?

In answer to LTolledo, I have examples of all of the 'classic outline' Raspberry Pis to date, but my question was in order to know whether my utility can be expected to work with all Pi models going back to the Pi 1 or whether it would be necessary to exclude early models from the 'this can be used ...
by SiriusHardware
Sat Feb 20, 2021 12:52 am
Forum: Advanced users
Topic: Maximum current available from +5V on GPIO connector?
Replies: 6
Views: 526

Maximum current available from +5V on GPIO connector?

I did search, the problem is not that this question has never been asked, but that it has been asked and answered so many times that there are a bewildering number of different answers. I'm making a small utility to read the contents of old PROM devices using a Raspberry Pi. As these PROMs are stric...
by SiriusHardware
Tue Oct 20, 2020 10:21 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Back onto the original topic after that very interesting diversion.. Another more obscure issue turned up in the 'send14' python script which supports the 'V2' version of the MK14-uploader described in my posts of March 27th 2019 - onwards earlier in this thread. When the 'autorun' feature was invok...
by SiriusHardware
Wed Sep 02, 2020 9:33 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Does more than my PROM reader sketch above, and the code only about one fifth as long. :)

I've saved a copy myself as a reference example of how it should be done!
by SiriusHardware
Tue Sep 01, 2020 6:40 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

EPROMs which contain the operating firmware of EPROM programmers present a particularly vicious paradox: If the programmer is the only programmer you have, how do you read and save the contents of the EPROM(s) in the programmer? It's a bit like trying to solder a new element into your only soldering...
by SiriusHardware
Sat Aug 22, 2020 7:54 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Strange one that. Assuming reset is active low, it's as though the reset input or reset circuit needs to see a falling edge before the rising edge, which will only happen if the power is on first (and reset not asserted) before it is then pressed and released. If there was a short, then you replaced...
by SiriusHardware
Thu Aug 20, 2020 9:20 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Not a bad start. :) If you have the means to do so you should maybe read and save backups of the code in the EPROMs, as they are probably getting to the age where bit-rot (data fade) could begin to be a problem. The trick of playing software in the form of audio into a retro system from a modern dig...
by SiriusHardware
Wed Aug 19, 2020 11:24 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Interesting looking system - your original image was obviously really good but the forum engine has downsized it to what it considers to be an acceptable size resulting in loss of detail. What processor is it based on? I can see 'i' (For Intel) on a 40-pin IC but I can't read the number. Quite a wel...
by SiriusHardware
Wed Aug 19, 2020 5:14 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Once again updating my own thread with new information. The 'send14' uploader script in the .zip file I attached to my post of 27th Mar 2019 for the 'MK2' version of the MK14 uploader has a silly bug in it - Any line of Intel Hex code which happens to have a checksum value of '00' is rejected (incor...
by SiriusHardware
Sat Jun 27, 2020 10:27 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Just updating my own old thread - I can now say that the Czech-made (Martin L) MK14 replica PCBs have the same keypad edge connector connection layout as original Science Of Cambridge MK14s, so if you have one of those use the opto-interface version for 'original' PCBs. The 'JM Precision' replica se...
by SiriusHardware
Sat Oct 19, 2019 5:32 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Manchester Encode/Decode [obsolete]
Replies: 8
Views: 5891

Re: Manchester Encode/Decode

While I see DougieLawson's point, that an old post may contain a solution / suggestion which will not work under a newer regime, in this case no progress had been made at all until Joan's suggestion, so there was nothing in this thread which had gone out of date. Even so, I would rather work through...
by SiriusHardware
Sat Oct 19, 2019 12:06 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Manchester Encode/Decode [obsolete]
Replies: 8
Views: 5891

Re: Manchester Encode/Decode

I can never understand why the -age- of the thread matters if it was never answered and the question remains exactly the same. Especially if New information or a new feature with some bearing on the question comes to light some time after the original post.

(The OP).
by SiriusHardware
Thu Jul 04, 2019 7:24 pm
Forum: Python
Topic: LCD 20x4 doesn't show text
Replies: 3
Views: 658

Re: LCD 20x4 doesn't show text

Try temporarily changing your rows=4 to rows =2 and see if that allows the code to work. To explain, the original HD44780 controller IC (on which most of these displays are based) only supports two lines, so when you have a 4-line display, what you really have there are two two-line displays each wi...
by SiriusHardware
Tue Apr 16, 2019 11:32 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

It's been brought to my attention that a modern MK14 replica could not accept keypresses at the default speed at which they were being sent to it by the uploader script ('send14'). This problem has been at least partly narrowed down to the particular 74LS365 chip which had been fitted instead of the...
by SiriusHardware
Thu Apr 11, 2019 7:57 am
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

That's already been done quite a long time ago for many of the more mainstream old computers like the Sinclair ZX81 and Spectrum, ie, a program which takes a saved file or memory snapshot file and converts it into the equivalent cassette audio output stream from a PC for playback into the retro syst...
by SiriusHardware
Wed Apr 10, 2019 10:43 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Here's the diagram of the interface as it needs to be modified for JM replica PCBs. You'll see that not only have some of the upper column lines been moved further down the MK14 edge connector but also, the two uppermost connections to the Pi's GPIO pins 5 and 7 are swapped. This is because on the o...
by SiriusHardware
Wed Apr 10, 2019 10:39 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: Old Meets New
Replies: 59
Views: 10626

Re: Old Meets New

Thank you! Unfortunately my work here is not yet done, as I have been informed that the Replica MK14 PCBs being offered by JM Precision in the UK have a different keypad edge connector pinout to that of my original issue II MK14. The type14 and send14 utilities in the zip file a couple of posts back...

Go to advanced search