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[ARM] STM discovery and EM4095

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Newbie level 1
Aug 26, 2015
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Hi all,

I wanted to ask for opinion since I have some issues with my project

I am working on a project that uses stm32-discovery board:

**broken link removed**

and Rfid reader: with EM4095.

My main goal is to receive code from rfid card and check if it exists in memory.

1. Since I am at the beginning of my project my first goal was to set everything up and to see if I receive any data from the board. I set SHD and MOD singals low.
My idea was to use RDY/CLK signal from the board (which is 125Khz clock) output as EXTI interrupt and to have a software timer that will be used for checking what data am I receiving. Is this a god approach?
First I wanted to have two hardware interrupts (one for RDY/CLK and the other one when there is a change on OUT) but I have heard from more experienced people that this causes some delays and may lead to incorrect data read? Is this true, or is this a better approach?
2. Other thing that I wanted to ask is this: it seems to me that this board is ALWAYS sending some data to the MC...even when there is no card near the board. I realized this when I tried that first approach. My program was always going trough both interrupt handlers...on for the clock (which is ok) and the one that was waiting either change of OUT data. I didn't understand from datasheets that this is something that is supposed to happen.

I'm sorry if the post is too long. Looking forward for your replies. If someone is willing to look at the codes I wrote please ask and I will post them here.

Thanks in advance.

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