Datasheet

FDS_6533_6534_004 71M6533/G/H and 71M6534/H Data Sheet
Rev 2 103
The maximum pulse rate is 3*F
S
= 7.5 kHz.
Control is transferred to the MPU for pulse generation if EXT_PULSE = 1. In this case, the pulse rate is
determined by APULSEW and APULSER. The MPU loads the source for pulse generation in APULSEW
and APULSER to generate pulses. Irrespective of the EXT_PULSE status, the output pulse rate controlled
by APULSEW and APULSER is implemented by the CE only. By setting EXT_PULSE = 1, the MPU is providing
the source for pulse generation. If EXT_PULSE is 1, W0SUM_X and VAR0SUM_X are the default pulse
generation sources. In this case, creep cannot be controlled since it is an MPU function.
PULSE_WIDTH allows adjustment of the pulse width for compatibility with calibration and other external
equipment. The minimum pulse width possible is 66.16µs.
The maximum time jitter is1/6 of the MUX cycle period (nominally 67 µs) and is independent of the number
of pulses measured. Thus, if the pulse generator is monitored for one second, the peak jitter is 67 ppm.
After 10 seconds, the peak jitter is 6.7 ppm. The average jitter is always zero. If it is attempted to drive
either pulse generator faster than its maximum rate, it will simply output at its maximum rate without
exhibiting any rollover characteristics. The actual pulse rate, using WSUM as an example, is:
Hz
XFWSUMWRATE
RATE
S
46
2
⋅⋅⋅
=
,
where F
S
= sampling frequency (2520.6 Hz), X = Pulse speed factor (as defined in the CECONFIG register
with the PULSE_FAST and PULSE_SLOW bits).
Table 64: CE Pulse Generation Parameters
CE
Address
Name Default Description
0x21
WRATE
171
Kh = VMAX*IMAX*66.1782 / (In_8*WRATE*N
ACC
*X) Wh/pulse.
0x22
KVAR
6448
Scale factor for VAR measurement.
0x23
SUM_PRE
2520
PRE_SAMPS * SUM_CYCLES (N
ACC
)
0x41
APULSEW
0
Wh pulse (WPULSE) generator input to be updated by the MPU
when using external pulse generation. The output pulse rate is:
APULSEW * F
S
* 2
-32
* WRATE * X * 2
-14
.
This input is buffered and can be updated by the MPU during a
conversion interval. The change will take effect at the beginning
of the next interval.
0x38
PULSEWIDTH
12
Register for pulse width control of XPULSE and YPULSE. The
maximum pulse width is (2*PULSEWIDTH+1)*(1/FS). The default
value will generate pulses of 10 ms width at FS = 2520.62 Hz.
0x42
APULSER
0
VARh (RPULSE) pulse generator input.
0x43
APULSEX
0
Pulse generator input for XPULSE output.
0x44
APULSEY
0
Pulse generator input for YPULSE output.
0x45
WSUM_ACCUM
0
Roll-over accumulator for WPULSE. A pulse is generated when
this register reaches 2
31
.
0x46
VSUM_ACCUM
0
Roll-over accumulator for RPULSE. A pulse is generated when
this register reaches 2
31
.
0x47
SUM2_ACCUM
0
Roll-over accumulator for the XPULSE pulse output.
0x48
SUM3_ACCUM
0
Roll-over accumulator for the YPULSE pulse output.