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zhangz64
Joined: 18 Jul 2013
Posts: 2
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| Help! TDC gp21 SPI not working |
 Posted: Thu Jul 18, 2013 12:21 pm |
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Hello, eveyone, we really need some helps from someone who has done gp21 SPI before.
Our team is trying to design a ultrasound imaging system which involves using the TDC-GP22 for the transducer.
We designed the transducer board our self.
Right now, We are trying to use Beagle-board to establish the communication with the transducer board through SPI interface.
Based on the information from the data sheet and the info here( http://www.ccsinfo.com/forum/viewtopic.php?p=160435 )
I coded the program myself, I used a GPIO to control the SSN line ,so it will be set to low before writing/reading the Data and set high after write/read.
Same goes for RESET, I set RESET it to low before writing/reading the Data and set high after the write/read.
I also confirmed the CLK/MOSI on the scope and so we know that we are sending the right Data. However, We failed to read anything back from the chip. We tested the MISO with the scope and it shows the read-back pulse but it is very weak.(200mv)
So we can not read anything back on the beagle-board,b/c the signal is too weak, We tried to re-solder some part and fix some potential short-circuit. but It did not work.
Does anyone know why is this happening.
It would be great if We could get some helps here.
Please advise.
Thanks |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Jul 18, 2013 1:07 pm |
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| Quote: | | We are trying to use Beagle-board |
Beagleboard is an ARM board. This is a CCS C compiler PIC forum.
It's focused on that, it's not a general electronics forum. We are not
allowed to give help on ARM projects. But to give you a hint before you
go, you shouldn't drop RSTN low during each SPI transaction. Pulse it
low at the start of main(), then keep it high after that. |
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zhangz64
Joined: 18 Jul 2013
Posts: 2
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| Posted: Thu Jul 18, 2013 1:47 pm |
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| PCM programmer wrote: | | Quote: | | We are trying to use Beagle-board |
you shouldn't drop RSTN low during each SPI transaction. Pulse it
low at the start of main(), then keep it high after that. |
Thank you so much PCM programmer.
I tried your method and set the Reset pin to 0 only at the start of the program.
It worked, I finally be able to read back from the register 1 and register 0.(but only 1 byte)
Well, it is something. |
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