Hello
I am using TRF7970A device in my project. I am interfacing the 13.56 XTAL external oscillator to it. When i am programming and operating the TX output is 6.78MHz. Please send the particular register setting for getting the 13.56MHz Tx output.
Regards
Sai
I even set the bit7 of 0x09 register to '0' but even then same problem. Please kindly advice.
Hello,
for sys_clk, you can set 3 bit of register 0x09.
b7 to 0, default crystal is 27.12MHz
b5 and b4 to 1, with crystal 13.56MHz SYS_CLK output is divid by 1 => 13.56MHz
set this register before register 0x01. bit B0 - B2 are changed when you set register 0x01 and modulation is wrong.
John
Hello John,
I am not saying about sys_clk output. Its about TX RF output.
Hello Sai,
Did you measure f_osc (either directly or by measuring sys_clk)?
Is osc_ok in the RSSI Levels and oscillator register 1?
I only got one case where the TRF's behaviour was completly weird, but I did not mesure the tx out frequency in this case. It had to do with EN2:
Page 19 of the datasheet:
When user MCU is controlling EN and EN2, a delay of 5 ms between EN and EN2 must be used. If theMCU controls only EN, EN2 is recommended to be connected to either VIN or GND, depending on theapplication MCU requirements for VDD_X and SYS_CLK.
Using EN = 1 and EN2 = 1 in parallel at start up should not be done as it can cause incorrectoperation.
Reagrds Marco
Sai -
i just responded to the email thread from Makarand - it looked to me like your schematic was incorrect as noted.
BR-
Josh
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