Component Advice Please?

[t0nyt]

I am afraid that will not do any good given the socket type on the QL is not hollow (at least on mine ) SO you would have to change the socket first to create space

Well the PCB won’t be sitting flush on top of the socket because of the plastic spacers on the legs and the centre of the QL socket is slightly lower than the edges.

I’ve compared dimensions with one of Chr$ ROM boards (which fit fine) and my measurements suggest it should fit

Only one way to be sure though!

The thing that really confuses me though is that the pictures of original boards I’ve seen are socketed!

[t0nyt]

I just tried bending the pins on a similar (spare) IC and it worked without any breaks

I then did a dry fit (along with EEPROM & QL socket legs) which shows just a bit of trimming on 74LS133 legs (under EEPROM) & one set of QL legs will allow all the parts to fit snuggly to the board

It comes out at the same height as one of Chr$ ROM boards and 74LS133 won’t need any space in QL ROM Socket

The big question is whether I can do it for real!

[t0nyt]

Decided to give it a go and see how I got on (haven't checked the soldering yet!)

All sockets removed and the 74LS133 is now upside down underneath (I didn't have any problems bending all the pins upwards). I can't see any reason why this wouldn't fit inside a QL height wise now, though yet to try it

Only tested it as a ROM and RTC, but all seems good

The top of the 74LS133 sits lower than the plastic collars of the QL legs so can't foul the QL socket

Edit: when I say “top” it’s actually the bottom of course

IMG_4768.jpeg (49.04 KiB) Viewed 349 times

[t0nyt]

I kept getting "xmit error" with i2c and now both boards also give that error when trying to set the time, or settings, as well using miniconfig_bas

Have decided to give up on this. At least I've had some soldering practice!

Many thanks

[javier2112]

It looks very nice! Have you published your solution? It'd be very helpful for other users.

Haven't published yet, still need to test the i2c as well. The battery holder fits a cr927, I am yet to see if the timekeeper current req of the smd pcf will make this a usuable solution.
That said, i can ofc share the gerbers if someone is also willing to test this (schematics is pretty much the same as the original). Just drop me a msg.

Thanks Arleybls for your offer, but unfortunetly, my only QL has just died

As soon as I have the chance, I'll start a thread about it .

[t0nyt]

I just had an epiphany

I put the socket less board inside of the QL instead of attached to the external ribbon cable (it fits inside ok, but I’ll need to remove the battery connector pins and solder the battery leads directly to the PCB)

Now the miniconfig_bas is working fine again

My program to control the LCD spectacularly crashes the QL, but it doesn’t error so I’ll revisit this when I can find some more time

Many thanks

[t0nyt]

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

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 MartynB on stardot for the original BBC code

Code: Select all

30  PROC_INIT
40  DIM M$(40) : M$="SINCLAIR QL         Minerva v1.98 Mk2"
50  FOR C=1 TO LEN(M$)
60   D$=M$(C TO C)
70   C%=CODE(D$)
80   H%=(C% && HEX('F0')) || HEX('09')
90   L%=((C%*16) && HEX('F0')) || HEX('09')
100   D%=H%:I2CTXB(D%) : REMark *I2CTXB 3F D%
110   PROC_EN
120   D%=L%:I2CTXB(D%) : REMark *I2CTXB 3F D%
130   PROC_EN
140 NEXT C
150 STOP
160  DEFine PROCedure PROC_INIT
170   DATA HEX('38'),HEX('38'),HEX('38'),HEX('28'),HEX('28'),HEX('88')
175   DATA HEX('08'),HEX('88'),HEX('08'),HEX('18'),HEX('08'),HEX('68')
180   DATA HEX('08'),HEX('E8'),HEX('88'),HEX('08')
190   RESTORE 170
200   FOR D=0 TO 15
210    READ D%
220    I2CTXB(D%) : REMark *I2CTXB 3F D%
230    PROC_EN
240   NEXT D
250  END DEFine
260  DEFine PROCedure PROC_EN
270   D%=D% || HEX('04')
280   I2CTXB(D%) : REMark *I2CTXB 3F D%
290   D%=D% && HEX('FB')
300   I2CTXB(D%) : REMark *I2CTXB 3F D%
310  END DEFine
500  DEFine PROCedure I2CTXB(D%)
510   LOCal r$
520   r$=I2C_IO(CHR$(164) & CHR$(D%) & CHR$(255),0,HEX('27'),1)
530  END DEFine

Many thanks all for the various advise

[techy]

nice result !!

[Derek_Stewart]

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?

[t0nyt]

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.co.uk/itm/263042637252 (looks like the same one I purchased)

Mine seems to have a TI version of the PCF8574 I2C control board as it defaults to address $27