TDC-GP21 datasheet(44/91 Pages) AMSCO

44 / 91 page

TDC-GP21

acam messelectronic gmbh - Friedrich-List-Str.4 - 76297 Stutensee - Germany - www.acam.de

3-19

parameter CYCLE_TEMP in multiples of 50 Hz or 60 Hz. The right selection of the

delay between the two measurements suppresses 50/60 Hz noise.

CYCLE_TEMP

factor

HZ60 = 0 (50Hz)

HZ60 = 1 (60Hz)

20 ms

16.67 ms

1.5

30 ms

25.00 ms

40 ms

33.33 ms

2.5

50 ms

41.67 ms



’h03, Start_Cal_Resonator: Triggers a calibration measurement of the high speed

oscilator. The TDC measures a time interval between 61 µs and 488 µs, specified

in ANZ_PER_CALRES. The end of the measurement is indicated by the interrupt.

The result, in multiples or the high speed clock period, is stored in result register

0. Dividing this by the theoretical value gives the correction factor.



’h04, Start_Cal_TDC: This command starts a measurement of 2 periods of the

reference clock. It is used to update the calibration raw data. Typically, the chip is

configured for auto-calibration and this command is not necessary.

3.4.2

SPI Sample

Figure 3-1: Sample scope picture for sequence INIT ’h70 and Start_Cal_TDC = ’h04

Member of the ams Group

TDC-GP21 Datasheet(PDF) 44 Page - ams AG