TRF7970AEVM: how to switch to DM1 mode after SDM success

oleg persidskiy

Prodigy 140 points

Part Number: TRF7970AEVM

Hi dear Engineers,

I'm struggling with a problem: no DM1 activated (no CLOCK on IO5 pin) after SDM success.

my steps:

1. send one byte (0x60 + 1 parity) use SDM mode. IO5 clock success.

2. send EOF frame

3. turn SS OFF (1) //stop SDM

4. write 0x10 with 0x00 / /exit SDM

** then, enter DM1 **

5. write 0x01 with 0x48 //(SS stays low)

6. write 0x00 with 0x60 //(SS stays low)

7. dummy write 0xFF //(SS stays low)

8. switch MISO mode to common input pin (SPI function disabled)

9. Waiting for The SDM CLOCK from 7970A ...... but unfortunately no clk signal exist on IO5 ....

Whats is wrong ?

thx.

over 7 years ago

0 Alex K. over 7 years ago

TI__Expert 7820 points

There is a TI design for the TRF7970AEVM that has SDM and DM1 working. It is located here:

http://www.ti.com/tool/TIDM-NFC-SDM?keyMatch=trf7970a&tisearch=tidesigns

There is source code available. Just a quick pointer, in the source code there is a file called directmode.c that has the SDM enter and exit then DM1 enter and exit.

Please take a look and let us know if you have further difficulty.

0 oleg persidskiy over 7 years ago in reply to Alex K.

Prodigy 140 points

Hi!

I,m just trying to perfom simply operation: get response to AUTH1 command (0x60 ,0x00) use DM1. but nothing work.

SDM TX success, because I can see clock signal on this pin (TRF IO5), also all oscillograms are according to SLOC214 document.

but after I turn the TRF7970 to DM1, no clock signal exist on IO5...

SDM command = 0x60,00 , with parity and CRC it's : 0x0160, 0x0100, 0x01F5, 0x017B

how to test DM1 mode really set or not ? thx.

0 Alex K. over 7 years ago in reply to oleg persidskiy

TI__Expert 7820 points

What hardware are you using - DLP-7970ABP (boosterpack), TRF7970AEVM or custom built?

0 oleg persidskiy over 7 years ago in reply to Alex K.

Prodigy 140 points

dear Alex!

I use

TRF7970AEVM

board PCB controlled by external Cortex M4F MCU.

both REQA / ATQA (0x04 for Mifare) and SELECT / SEK (0x08 for Mifare) the signals are ok.

maybe I'll put some oscillograms to here. but I already checked 3 times, it fully matched to SLOC214 document....

0 oleg persidskiy over 7 years ago in reply to oleg persidskiy

Prodigy 140 points

I just increased the response time delay from 50us to 200 us and now I see the response data from TRF7970A with ~ 100us delay...
but another problem , this data RANDOMLY changed with correct Parity.
request: 0160 0100 01F5 017B (with parity)
response: random data 3 ... 15 bytes of lengh but with correct Parity!

I dont understand why?

thx

0 oleg persidskiy over 7 years ago in reply to oleg persidskiy

Prodigy 140 points

OK, I find an error in the source code of SLOA214 example in function Mifare_DM1_Recieve(..);
I changed the algorithm behavior of RX pin polling procedure (0->1 data reading time; 1->0 data changing time).
now all right.
thx a much !!!

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