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Forum Index : Microcontroller and PC projects : 1-Wire Comms - First time user...
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Zonker Guru  Joined: 18/08/2012 Location: United StatesPosts: 767 |
Good morning gents... I have a small project I want to do getting data from a DS28EA00 Thermometer IC monitoring the temp of a PCB here at work... I tried to upload the 1.09 meg PDF file for the IC, but the up-loader says it's to big... I am using the R pi pico waveshare LCD 0.96 board to do the programming on, with version 5.07.06 firmware installed... There is only one IC connected so I am using the "skip ROM" (&hCC) command to get access to the commands... The commands I am using are Convert Temp (&h44), and Read Scratchpad (&hBE) I have a scope connected to the data line and am seeing the reset and data... OneWire write GP27,1,2,&hCC,&h44 'send skip ROM & Convert temp command (reset before) PAUSE 1000 ' 750ms for a 12 bit convert OneWire write gp27,1,2,&hCC,&hBE 'send skip ROM & Read Scratchpad memory (reset before) OneWire read gp27,2,2,temp_lsb,temp_msb 'get the temp data (reset after) The chip seems to be sending the data back but how do I properly capture it using the OneWire read command..?? After sending the read scratchpad memory command, the chip sends the data immediately and I don't think I am getting the correct data back... Was hoping to find a 1-wire expert out here for some advice... Thanks in advance for any help with this..!!  |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4044 |
You could post a link to the PDF. There are some rather old (ca-2020 etc) posts which might help, including some code (e.g. by Chopperp). Maybe more on fruitoftheshed? John |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Thanks John... I will take a look around and see if I can find more on this... Thanks for your help...  |
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TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
I was playing around with one-wire on the pico some time ago. I came to the conclusion that the time between the write and following read is too long. I did not follow on with the investigation unfortunately. Can you try running the pico at maximum speed. Jim VK7JH MMedit |
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| TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6283 |
It might sound silly, but have you tried treating as a DS18B20? Use the TEMPR function and see what happens. Jim VK7JH MMedit |
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9610 |
Watching this thread with MUCH interest, as I am about to start playing with the DS28E07 memory IC on the 1-wire bus, but I will likely start my own thread on that - unless everything works and I have no issues, but I expect there might be some, as I too have never used the 1-wire commands. Smoke makes things work. When the smoke gets out, it stops! |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4044 |
If it's not fast enough going from Write to Read maybe a WriteAndRead is needed? John |
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| Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 767 |
Evening Gents... As it turns out, Tassy Jim was spot on... I took a look at both PDF data sheets and except for the I/O, they work the same protocol... Worked like a champ... I do think we need to figure out how to make the 1-wire functions work right... Maybe they do work right and I just don't know how to get an example working correctly... I think I saw the part answering the Read Scratchpad command before I could get the One wire read function called... I think it was causing the garbled data I was getting.. (not sure)... Anyway, I think we should be able to connect more 1-wire ICs and figure out how to use the code... It would be awesome to have an easy function to handle the search & serial # handling too.. With 1 MPU I/O line you could make multi device nets... I might buy some interesting 1-wire ICs and do some tinker...  Thanks... |
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