Scope I'm trying to interface the Arduino (Nano) with the NXP chip HTRC110. The datasheet of HTRC110 and the application note are there : http://www.nxp.com/documents/application_note/AN98080.pdf http://www.nxp.com/documents/data_sheet/037031.pdf
The chip communicates through a similar SPI with the Arduino Nano : DIN, DOUT, SCK (no Chip Select). I have implemented that communication and I manage to configure the different registers of the chip and to re-read them back and confirm what I've done. So the communication with the chip is well established and works. DIN and DOUT are sync with CLK as expected, its all good.
Problem My problem is when I need to read a tag. According to the datasheet/AN, one should send with the Arduino, three '1', to make the chip entering in the reading process. Through all I've read on the internet, the CLK need to be SET LOW after the 3 '1's are sent, which I do in my code. Normally commands are one byte but the reading is specific and is '111' + CLK Low. So well, I've done that but I have two problems :
When I look the RF driving signal at the output of the chip (or if I look the RF signal with a loop probe), I don't see any modulation in the driving signal or in the EM field.
I have things on Dout (Chip -> Arduino line), but it's erratic. It looks like it changes when I approach a tag to the antenna but still, it looks random so I can't tell, I can't indentify what I'm seeing on the oscilloscope.
What have I done wrong ? There's no chronogramme or anything in the datasheet and I havent found a lot of information ... I've seen some people had same troubles as I have but I havent found any followings in their topics. So I don't know whether they gave up or found a solution.
If someone has implemented that chip, even if not with an Arduino, I'd be very grateful for any kind of help. Thanks all.