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Member Since 01 Dec 2012
Offline Last Active Jan 20 2013 08:58 AM

Posts I've Made

In Topic: GoBus ports reading speed

18 January 2013 - 07:27 PM

Thank you for your help! I guess I misunderstood the Go Bus. 


Back to the drawing board...  :rolleyes:

In Topic: Help with reading what looks like SPI but isn't

03 December 2012 - 06:32 PM

Thank you both for your answers!

I've recorded the signal with bus pirate, and if I counted it right, clock has 400kHz frequency, Clock HI time is 1.5us and clock LO is 0.75us (according to what the bus pirate recorded). Gap between words is 3us. Will netduino be able to read it as 3 separate digital signals on interrupt mode or is it too fast? Here is the pic what the signal looks like:

Posted Image

In Topic: Help with reading what looks like SPI but isn't

02 December 2012 - 06:29 PM

Thank you for the welcome and for a quick and detailed reply!

I've been reading your answer and it seems to me that this will work the other way around then I need it to work.

Netduino is suppose to read those 11 words, not send them. I get a clock, data and load signal from a device and am trying to send them to netduino so it can read them and store in an array(instead of the MSM6775). The problem is that I read in the wiki that netduino is the master and as master it is the one that sends the clock, data and load signal, not receives it.

I was looking at this option for reading the data but I'm not sure if it will work:

"The SPI bus is full-duplex. That means that data is sent simultaneously in both directions. The bus is controlled by the bus master, in this case the Netduino. The slave device cannot send data back unless the master generates the clock pulses. So whenever we want to read data we need to send enough clock pulses to get the data we want out. At the same time as the slave is sending data on its DOUT or MISO line, it is also reading whatever is on its DIN or MOSI line, even if this is 0xFF (all ones) or 0x00 (all zeros). So you cannot read without writing to the slave at the same time. That is why there is no SPI.Read() function."

As far as I understood it, if netduino sends 11 byts of clock pulses same frequency as the device has, it will read 11 words back, but the chances that timing of netduino reading the data and device sending it at the same time are probably close to none.

I found another idea in this project that is similar to what I'm trying to do:, with difference that I won't be displaying the data on another segment display. That's why I need that data in the netduino and I'll process it in another way later on.
At the end of the page it is explained how to trick the chip into reading data as SPI with false LOAD signal every 8 bits, but this would need netduino to work as SPI slave to read it and I know it's not that easy to do.

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