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DrifterNL

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Joined: 27/09/2018
Location: Netherlands
Posts: 58

Posted: 09:20pm 02 Jun 2024

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Just a suggestion / request.
Using the I2C commands I2C(2) WRITE addr, option, sendlen, senddata.... and I2C(2) READ addr, option, rcvlen, rcvbuf
I would like to be able to set the sendlen or rcvlen to 0 (with option auto set to 0) so that just the I2C write address or I2C read address is sent without writing / reading any further data.

[s][I2C Write Address][ack][p]
[s][I2C Read Address][ack][p]

This would make it easier searching the I2C bus for devices, using the general call address 0 and probably a few other things concerning the I2C Bus.

or maybe there is an option already to do this that I overlooked?
Greetings,
DrifterNL

Floating Point Keeps Sinking Me!
Back To Integer So I Don't Get Injured.

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2135

Posted: 10:10pm 02 Jun 2024

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This scanner isn't too complicated (PicoMite):-

> SetPin gp0, gp1, I2C :i2c open 100,1000
> for i=0 to 127 :i2c write i,0,1,0 :If MM.I2C=0 Then :? hex$(i,2):endif:next
57
68
>

DrifterNL

Regular Member

Joined: 27/09/2018
Location: Netherlands
Posts: 58

Posted: 10:24pm 02 Jun 2024

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phil99 said This scanner isn't too complicated (PicoMite):-

> SetPin gp0, gp1, I2C :i2c open 100,1000
> for i=0 to 127 :i2c write i,0,1,0 :If MM.I2C=0 Then :? hex$(i,2):endif:next
57
68
>

True, but doing it that way you could inadvertently be writing a 0 into an I2C device setup / command / data register.

Floating Point Keeps Sinking Me!
Back To Integer So I Don't Get Injured.

phil99

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Joined: 11/02/2018
Location: Australia
Posts: 2135

Posted: 10:45pm 02 Jun 2024

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I don't think any of the devices I have use the first byte for anything.
I assume this is deliberate to prevent scanners affecting anything.

Edit
Or if the first byte is used perhaps it is read-only.
Tested the scanner on everything I have and nothing was affected.

Edit 2
Looked at a couple of datasheets where the first byte is a command or part of a command.
However a value of 0 does nothing on those devices.

There are a number I2C scanners on this forum that use the same method and no one has reported any problems with any device so it seems safe.
Edited 2024-06-03 10:37 by phil99

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