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Rigol MSO5074 Logic Analyzer issues

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jerryk:

--- Quote from: Kean on September 25, 2024, 12:24:52 pm ---If this is a character LCD with an I2C interface via a I2C GPIO IC, then you will likely find that it is only using 4-bit mode.
Typically the 8-bit GPIO provide 4 data bits and 3 control signals to the parallel bus input of the LCD.
That would explain why you cannot find the letter "P" in the data stream.

--- End quote ---

That reality became evident shortly after I was able to get the initialization sequence working.  I could see all the hex values of the init commands stream by and the LCD turned on perfectly as commanded.  The reason it worked was because I sent the data in the init sequence in 8-bit mode and all the control bits default to 0.  I then sent the character stream of my name to the LCD.  It decoded perfectly and I could read it on the event table on the scope yet just the letter "o" showed on the LCD.  Now that understand that 4-bit mode is necessary for characters and that I will never see the decoded ascii characters on any LA, going forward should be a bit easier.  I also need a clearer understanding the 8 bit I/O expanders function.

Jerry

Jerry

tggzzz:

--- Quote from: jerryk on September 25, 2024, 06:03:09 pm ---
--- Quote from: Kean on September 25, 2024, 12:24:52 pm ---If this is a character LCD with an I2C interface via a I2C GPIO IC, then you will likely find that it is only using 4-bit mode.
Typically the 8-bit GPIO provide 4 data bits and 3 control signals to the parallel bus input of the LCD.
That would explain why you cannot find the letter "P" in the data stream.

--- End quote ---

That reality became evident shortly after I was able to get the initialization sequence working.  I could see all the hex values of the init commands stream by and the LCD turned on perfectly as commanded.  The reason it worked was because I sent the data in the init sequence in 8-bit mode and all the control bits default to 0.  I then sent the character stream of my name to the LCD.  It decoded perfectly and I could read it on the event table on the scope yet just the letter "o" showed on the LCD.  Now that understand that 4-bit mode is necessary for characters and that I will never see the decoded ascii characters on any LA, going forward should be a bit easier.  I also need a clearer understanding the 8 bit I/O expanders function.

--- End quote ---

Logic analysers analyse bits. If you capture a nybble, any logic analyser will represent it as a hex character.

Protocol analysers analyse messages.

Choose your tool according to what you are trying to do.

Having said that, with a little practice it is possible to read holes in 8 channel paper tape (not 5 channel!). Thus, particularly if you know what you are looking for, mentally converting pairs of hex digits into the common ASCII character becomes second nature.

Howardlong:

--- Quote from: tggzzz on September 25, 2024, 06:24:52 pm ---
Having said that, with a little practice it is possible to read holes in 8 channel paper tape (not 5 channel!). Thus, particularly if you know what you are looking for, mentally converting pairs of hex digits into the common ASCII character becomes second nature.

--- End quote ---

I dunno, I used to read 5 hole paper tape and fix minor typos with my Algol programs using a manual hand punch and some spare chad back in the 70s.

It wasn’t that long ago that reading protocols like I2C off a scope trace with pen and paper was a thing.

tggzzz:

--- Quote from: Howardlong on September 25, 2024, 07:54:35 pm ---
--- Quote from: tggzzz on September 25, 2024, 06:24:52 pm ---
Having said that, with a little practice it is possible to read holes in 8 channel paper tape (not 5 channel!). Thus, particularly if you know what you are looking for, mentally converting pairs of hex digits into the common ASCII character becomes second nature.

--- End quote ---

I dunno, I used to read 5 hole paper tape and fix minor typos with my Algol programs using a manual hand punch and some spare chad back in the 70s.

It wasn’t that long ago that reading protocols like I2C off a scope trace with pen and paper was a thing.

--- End quote ---

Tony Hoare's Algol-60 compiler on an Elliott 803 perhaps? I presume you have been to TNMoC, seen one working, and discussed the schematics?

Decoding serial ASCII, e.g. a UART, is a chore.

Howardlong:

--- Quote from: tggzzz on September 25, 2024, 09:15:02 pm ---
--- Quote from: Howardlong on September 25, 2024, 07:54:35 pm ---
--- Quote from: tggzzz on September 25, 2024, 06:24:52 pm ---
Having said that, with a little practice it is possible to read holes in 8 channel paper tape (not 5 channel!). Thus, particularly if you know what you are looking for, mentally converting pairs of hex digits into the common ASCII character becomes second nature.

--- End quote ---

I dunno, I used to read 5 hole paper tape and fix minor typos with my Algol programs using a manual hand punch and some spare chad back in the 70s.


--- End quote ---

Tony Hoare's Algol-60 compiler on an Elliott 803 perhaps? I presume you have been to TNMoC, seen one working, and discussed the schematics?

--- End quote ---

That's the one. It was donated to the school I attended by a local engineering firm. The pupils maintained it, self-taught, with negligible teacher involvement. There were a couple of teleprinters to write the code. One of my peers was especially good at fixing the teleprinters: a good job as they often went wrong.

The curator of the 803 at TNMoC is (or was) at the same school, a year ahead of me. We still occasionally chat on Facebook.

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