The Sinclair QL Forum

Silvester wrote:

Martin_Head wrote: I have been toying with the idea of writing a driver for the Q68's I2C bus.

IMHO it would be impractical to use a driver to control I2C. Minerva's way of doing it seemed best and gives complete control of the bus.

I've kind of been coming to that conclusion as I have been thinking about how to send and receive data.

Tinyfpga wrote:I don't know how to use the I2C bus.

See Minerva's implementation http://www.dilwyn.me.uk/docs/manuals/mi ... ual_11.pdf Page 53 onwards.

Although you'll need to be familiar with I2C generally and target device datasheets. Ian Burkinshaw wrote some interesting articles on i2C with QL http://www.dilwyn.me.uk/docs/hardware/IanB/ianb.html

I will take a look at the above. My Minerva manual does not have any of the MK2 stuff in it. I saw the I2C_IO_BIN file on the Minerva disk. Which I plan to disassemble.

The thing is, I don't have any experience of I2C, and I don't have any I2C devices. I've started writing some assembler bit banging code based on the Wikipedia I2C page, and I'm thinking about testing it by trying to read and write to the Q68 backup clock chip.

Also I'm thinking that the Minerva I2C stuff may be in the Minerva source code, which may be worth looking at.

Hi,

The Minerva I2C_IO_BIN file adds a function I2C_IO, which uses the Minerva ROM routines to access the I2C interface.

While the i2C Hardware sold by Tony Firshman maybe be compatible with the Q68 I2C interface, the Minerva I2C ROM routines detailed in the ROM source code may need sole conversion to the Q68.

I was going to reproduce the TF Services I2C hardware devices, but I think more modern version can be bought.

I also did not put an external I2C interface on the current Q68 case, which I will change in the next batch of Q68.

nop

Hi,

Looks like my assumption that there was I2C code in the Minerva ROM was incorrect.

Looking at the file I2C_IO_REXT_dis, the base of the Minerva MKII I2C hardware is at $BFDC, which located in the ROM space, is there accomodation in the Minerva ROM to include the I2C Hardware?


Which may mean, using SMSQ/E will make the I2C interface unusable, or am I wrong again...

The I2C "hardware" is a GAL chip that's used in conjucton with some I2C primitive code to give basic I2C funtionality - a driver on a seperate disk provides the rest of the code required to use I2C from Basic / Assembler. There is a new vector for I2C provided by Minerva.

Pr0f wrote:The I2C "hardware" is a GAL chip that's used in conjucton with some I2C primitive code to give basic I2C funtionality - a driver on a seperate disk provides the rest of the code required to use I2C from Basic / Assembler. There is a new vector for I2C provided by Minerva.

The Minvera I2C code is in the folder Ii in the source code for Minvera.

Martin_Head » Sun Feb 20, 2022 9:27 am The thing is, I don't have any experience of I2C, and I don't have any I2C devices.

I thought I would see what I2C devices one can buy. There are plenty of them:- Digital compasses, 3-axis accelerometers, gyroscopes, Ambient light, Spectroscopy, Lidar, Relays, Distance, etc. When I tried to actually buy a device I found them to be on back order with no known delivery date.

I tried Adafruit and had more luck. They list I2C temperature, humidity, pressure and altitude sensors in stock at low prices.
Would you like me to send you some?

Martin_Head wrote:Has anybody done anything with the Q68's I2C bus yet?

Yes, when I wrote the clock support for the Q68 loader and the Q68SETRTC tool.

I also tried the TF interfaces. Example code here: viewtopic.php?f=20&t=2869&hilit=I2C&start=10#p28317

As for printer connectivity, there are a number of Postscript Printers with Ethernet, maybe some of them work with the Q68 (hoping that the postscript data can simply be copied to a specific TCP port like on old postscript printers).

Ok, slightly back to topic:

Does anyone know how far the OS for Futura had progressed? Does it exist? Has Urs (Hello Urs) possibly found anything in the EPROMs, if any? Dave maybe? Is there any circuit diagram for Futura?

RalfR wrote:Sandy has written that the board is 215x225mm, that is contrary to the PCB Urs has and what Dave said.

I had to photocopy a board for part placement testing, and it would just not quite fit on an A4 piece of paper. I do not recall if it was the short or long edge. I am recalling things from my quite fussy memory that happened in the mid-80s, so contemporaneous documentation should always be given higher standing than my sometimes flawed recollections.