Re: Adventures with I2C & Minerva Mk2
Posted: Tue Sep 09, 2025 3:40 pm
Well it _looks_ simple enough... have ordered a couple to have a play
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Adventures with I2C & Minerva Mk2
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Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 6:27 am
Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 6:33 am
Looking at the CAD drawing for the Mk2 remake it doesn't look like there are any pull up resistors on the mk2 board
I'm wondering if the odd things I'm seeing with a couple of devices could be down to a lack of pull-up's?
Could I cause any damage by fitting a couple of 10k resistors somewhere between the mk2 and the i2c devices please?
I understand what they do to the i2c bus, but am not confident enough to just shove them in yet
Many thanks
Tony
I'm wondering if the odd things I'm seeing with a couple of devices could be down to a lack of pull-up's?
Could I cause any damage by fitting a couple of 10k resistors somewhere between the mk2 and the i2c devices please?
I understand what they do to the i2c bus, but am not confident enough to just shove them in yet
Many thanks
Tony
Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 8:06 am
No damage at all.
Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 8:09 am
Many thanks, will try fitting a pair just before the breakout board to see what happens then
Many thanks
Tony
Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 8:26 am
Because you are using lots of flying wires you might be reaching the capacitance limit on the bus.
Time to learn kicad and get some PCBs
Time to learn kicad and get some PCBs
Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 8:31 am
MaybeXorA wrote: Wed Sep 10, 2025 8:26 am Because you are using lots of flying wires you might be reaching the capacitance limit on the bus.
Time to learn kicad and get some PCBs
But the devices in question (like 32kb) still play up when connected directly to bus on their own without the breakout
Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 8:46 am
Mind you, the device I have most trouble with has it's own pull up resistors on-board, so I may be barking up the wrong tree here (for now at least)
EDIT: the problem device is working now, was a slog though
EDIT: the problem device is working now, was a slog though
Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 2:09 pm
Next up Text-to-Speech (DFROBOT Speech Synthesis Module)
This has an address ID of &80 (i2c_io &40) - which clashes with HTU21D Temp/Humidity, so to use both will need a mux (thanks XorA)
So far, for some reason that I'm looking into, I can only get the same female voice regardless of the [m] option setting
Downsides of this module (other than using &80) are that the "English" voice has a distinct Chinese twang (no offence!) and the built-in speaker is a bit "tinny" so will be trying the audio out to my QL monitor when I get a chance.
This is a VERY basic test program, will eventually create a full library of the available functions and settings
The basic BASIC code
The device for those who haven't seen one before
This has an address ID of &80 (i2c_io &40) - which clashes with HTU21D Temp/Humidity, so to use both will need a mux (thanks XorA)
So far, for some reason that I'm looking into, I can only get the same female voice regardless of the [m] option setting
Downsides of this module (other than using &80) are that the "English" voice has a distinct Chinese twang (no offence!) and the built-in speaker is a bit "tinny" so will be trying the audio out to my QL monitor when I get a chance.
This is a VERY basic test program, will eventually create a full library of the available functions and settings
The basic BASIC code
Code: Select all
100 c$=CHR$(164) & CHR$(HEX('AA')) & CHR$(255)
110 r$=I2C_IO(c$,0,HEX('40'),1)
120 c$=CHR$(1) & CHR$(188) & CHR$(255)
130 r$=I2C_IO(c$,1,HEX('40'),1)
200 PAUSE 50
500 t$="[x0][t5][v5][s6][m3][g2][h2][n1]This is a test of speech"
510 c$=CHR$(164)
520 c$=c$ & CHR$(HEX('FD')) : REMark command header
530 c$=c$ & CHR$(0) & CHR$(LEN(t$)+2) : REMark command length
540 c$=c$ & CHR$(1) & CHR$(0) : REMark synth text
550 c$=c$ & t$ : REMark text to speak
560 c$=c$ & CHR$(255)
570 r$=I2C_IO(c$,0,HEX('40'),LEN(t$)+5)Re: Adventures with I2C & Minerva Mk2
Posted: Wed Sep 10, 2025 3:28 pm
Next up BH1750 Light Sensor
This uses address &23 by default, but can be changed to &5C which I had to do as &23 is used by the TI LCD (though I've just remembered that I could of just changed the address on that. Doh. (of course the &5C clashes with the "phantom" address of the 32kb eprom so had to re-jumper that as well)
I don't have a light meter so can't validate the Lux reading, but the lux value increases/decreases depending on the light shone on it
The code
The device
This uses address &23 by default, but can be changed to &5C which I had to do as &23 is used by the TI LCD (though I've just remembered that I could of just changed the address on that. Doh. (of course the &5C clashes with the "phantom" address of the 32kb eprom so had to re-jumper that as well)
I don't have a light meter so can't validate the Lux reading, but the lux value increases/decreases depending on the light shone on it
The code
Code: Select all
100 REMark Perform a power on and clear last measurement for testing purposes
110 c$=CHR$(164) & CHR$(HEX('01')) & CHR$(255): REMark Power on to allow clear
120 r$=I2C_IO(c$,0,HEX('23'),1)
130 PAUSE 5 : REMark need pause after power up?
140 c$=CHR$(164) & CHR$(HEX('07')) & CHR$(255): REMark Clear Last Reading
150 r$=I2C_IO(c$,0,HEX('23'),1)
160 PAUSE 5 : REMark need pause after clear?
200 REMark Send Measurement request for One Time Hi Res Mode
210 c$=CHR$(164) & CHR$(HEX('20')) & CHR$(255)
220 r$=I2C_IO(c$,0,HEX('23'),1)
230 PAUSE 10 : REMark pause for about 200ms (120ms needed)
300 REMark Request Measurement 2 bytes
310 c$=CHR$(188) & CHR$(255)
320 r$=I2C_IO(c$,3,HEX('23'),2)
330 v=CODE(r$)*256
340 v=v+CODE(r$(2 TO 2))
350 v=INT(v/1.2)
360 PRINT v;" Lux"- IMG_5056.jpeg (66.21 KiB) Viewed 9 times