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Run into some troubles using the reader CR95HF

Question asked by lamotte.thierry on Feb 17, 2015
Latest reply on Feb 18, 2015 by Marchese.Graziella
Dear All,

We designed a RFID reader using the chip CR95HF. We use quite old SRI4K tags. We used the ST lib (lib_SRIX4k.c from the MMY Application Team) that manages this tag.

The hardware design follows the typical schematics and bill of materials.

Some of our boards work well, other do not and we do not know exactly why. So we would appreciate some help to understand the causes:

For instance, when it fails, a deeper analysis says:
- The communication between the host and the CR95 uses the UART channel. This communication works pretty well.
- the response to the Protocol Select is 0x00 0x00. So, according to the function
CR95HF_IsReaderResultCodeOk(), it sounds Ok.
- The response to the "Initiate" gets weird since it does not correpond to any expected returned codes (i.e. 0x80, 0x86, 0x87 etc.): We got 0x00 and 0x00. Still, according to the function CR95HF_IsReaderResultCodeOk(), it failed.

Please, could tell us what the Error Code 0x00 means when sending the "Initiate" or, more generically, when the Command Code is SEND_RECEIVE?

Another point for which we may have some doubt: On the same board, both power supplies VPS_Main and VPS_Tx are generated from a DC-DC switching power supply. Is it a recommended?

Thanks a lot for your help,