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HF RFID response time using TRF7960EVM with the MSP430F2370 MCU

Vladimir Nohava
Prodigy 185 points


Hello,

Playing around with the TRF7960EVM, I hooked up my scope and set the following under the TFF7960 EVM control application under Test t ab using Firmware Revision 06_16_2011 (programmed LED5 to have trigger out)

0x10 Write single register - Chip Status Control (00h) "21" and ISO Control (01h) "06"
010C00030410002101060000 = 1000210106

0xF0 AGC selection, 0x00 – AGC enable or 0xFF – AGC disable
0109000304F0000000 = F000

0xF1 AM/PM input selection - 0x00 – FM input or 0xFF – AM input
0109000304F1FF0000 = F1FF

0x18 Request command ISO15693 - Cmd = 20, Read Single Block (no option flag), block "00"
010B000304180320000000 = 18032000 - flags = 03, FSK, HIGH bit rate

Reading block 00 from the tag. I noticed that if i leave the tag within the vicinity of the reader and let  the reader read over and over. I notice sometime the tag doesnt respond. See please attached screen grabs of a good trigger and bad trigger.

What conditions are needed to generate this trigger pulse?

Why does the tx of the reader only start 1.78mSec after falling edge of the trigger pulse? can this length be a varible to set the time shorter?

Same goes the for timing between the TAG EOF and the next trigger pulse edge (@1.2mS)

Does the Reader generate the IRQ signal that we measure on the pin or has it been conditioned by the MCU?

While in stand alone (viewing the LEDs blink) is it using the same setup (configurations) as working with the EVM control application?

 

GOOD

 

BAD

 

once in the 15693 tab we set protocol to read single block, double sub-carrier, high data rate.

We read blocknumber 00 and I can monitor on the scope a continious read of block 00 (as seen in capture images above).

Trying to do any other command like change protocol setting causes the application to crash.Perhaps the image i download for the MCU is not the latest and greatest?

We are using TRF7960A C Code Samples  at http://www.ti.com/product/trf7960a, even though our chip is trf7960 with rev A pcb.  I see no source code for trf7960 to set the led5 to be a trigger signal (only for trf7960a)

Thanks

Vlad