[time-nuts] schematics of frequency counter

[Li Ang]

Hi
   Today I did the same test without these 2 oscillators. The stddev on
20141228 data is 149ps. The stddev of today is 97ps. According to the new
datasheet, stddev will be lower if set to 45ps resolution mode. I did that
and got 76ps stddev. The datasheet does not lie to me :).

  Data is uploaded to
http://www.qsl.net/b/bi7lnq//freqcntv4/test/20150108/tdc_stddev.xls

The configuration of tdc-gp22 is now:
    Register_0 = 0x00c42700,
    //Register_1 = 0x19498000, //stop2-stop1
    Register_1 = 0x01418000,//0x01418000, //stop1-start,
    Register_2 = 0xe0000000,
    Register_3 = 0x00000000,
    Register_4 = 0x20000000,
    Register_5 = 0 << 27,
    Register_6 = 1 << 12;



2015-01-06 7:33 GMT+08:00 Li Ang <lllaaa at gmail.com>:

> Hi Bob,
>   There are 2 oscillator on board, one 8MHz for MCU one 125MHz for FPGA.
> I've took it down from the board, and changed MCU to use internal RC
> oscillator for MCU and PLL to mutilply refclk to 200MHz for FPGA.
>   I will try do the same test tonight thanks.
>
>
>