Struggling with EEPROM addressing ...

[Michael]

Well done folks!!

You were both correct:
- first I corrected the Rx <-> Tx thing and still no joy ...
- then I grounded CTS and BOOM!

[epaell]

Fantastic! Great to hear Michael!

[Editor]

The Tx and Rx on my board (the green one) correspond to the silk screen markings on the waveshare and velleman FTDI devices (and the pinout of the ftdichip.come cable connector.
The ones on the MECB I/O card correspond to the pins on the 6850!! (the opposite)

I notice the "FTDI" connector on your green PCB is the same pin-out as the connector on MECB (FTDI standard). Just that yours doesn't have the CTS / RTS pins, and mine doesn't have the 5V input pin.

But, are you saying that on your green board, the Rx / Tx are transposed to the ACIA pins that they connect to? (So your Rx pin is actually the ACIA Tx output?).

Serial connections will always be confusing!

[Michael]

But, are you saying that on your green board, the Rx / Tx are transposed to the ACIA pins that they connect to? (So your Rx pin is actually the ACIA Tx output?).
Serial connections will always be confusing!

Pretty much. I followed the convention from the other FTDI devices that I have pinouts for : they are done from the perspective of the client connecting (and they are right there on the silkscreens of their little boards - would have been super confusing to have the opposite).

Grant Searle annotates both sides in his diagram but this sealed the deal for me in terms of what the 'standard' is for the most common cable plug. Your Tx and Rx pins are flipped which could be more of an issue than the silkscreen (I assume you have a cable that cleverly does the opposite?)
http://searle.x10host.com/6502/Simple6502.html


Yes, not a new problem, and I don't think there is a good answer other than "check!"

I grew up with "is it null modem or straight through", and, being horribly dislexic, I would keep flip-flopping the answer.
Hence the little red strips on all my connectors (I included 'CTS to GND' inside my little cross-over bodge connector).

[lenzjo]

Pretty much. I followed the convention from the other FTDI devices that I have pinouts for : they are done from the perspective of the client connecting (and they are right there on the silkscreens of their little boards - would have been super confusing to have the opposite).

Grant Searle annotates both sides in his diagram but this sealed the deal for me in terms of what the 'standard' is for the most common cable plug. Your Tx and Rx pins are flipped which could be more of an issue than the silkscreen (I assume you have a cable that cleverly does the opposite?)

Yes, not a new problem, and I don't think there is a good answer other than "check!"

I grew up with "is it null modem or straight through", and, being horribly dislexic, I would keep flip-flopping the answer.
Hence the little red strips on all my connectors (I included 'CTS to GND' inside my little cross-over bodge connector).

This is why do the SMD dance on all my boards, little chance of an error with a usb cable

[djrm]

Pin naming aside I find it convenient to set the uart RTS line active so that it can be connected to the FTDI CTS input. This removes the need to ground the RTS input to the FTDI and means that if an interface is expecting RTS/CTS handshaking then the pins will already be configured properly. A small change to the Assis09 ACIA setup function is needed to accomplish this:

Code: Select all

* CION - INPUT CONSOLE INITIALIZATION
* COON - OUTPUT CONSOLE INITIALIZATION
* A,X VOLATILE
CION   EQU      *
COON   LDA      #$3             ; RESET ACIA CODE
       LDX      <VECTAB+_ACIA   ; LOAD ACIA ADDRESS
       STA      ,X              ; STORE INTO STATUS REGISTER
       LDA      #$11            ; SET CONTROL
       STA      ,X              ; REGISTER UP
RTS    RTS                      ; RETURN TO CALLER

With done then I can use this all-in-one USB FTDI cable, albeit with some rejigging of pins in the 6 way connector.
https://www.aliexpress.com/item/1858974923.html


6 way shell changes:


hth David.