Rainbow Electronics DS1687 - Manual (Page 17)

DS1685/DS1687
17 of 38
Register B. The periodic interrupt can be used with software counters to measure inputs, create output
intervals, or await the next needed software function.
Table 2. PERIODIC INTERRUPT RATE AND SQUARE-WAVE OUTPUT
FREQUENCY
EXT. SELECT BITS REGISTER A
E32K RS3 RS2 RS1 RS0
t
PI
PERIODIC
INTERRUPT RATE
SQW OUTPUT
FREQUENCY
0 0 0 0 0 None None
0 0 0 0 1 3.90625ms 256Hz
0 0 0 1 0 7.8125ms 128Hz
0 0 0 1 1 122.070µs 8.192kHz
0 0 1 0 0 244.141µs 4.096kHz
0 0 1 0 1 488.281µs 2.048kHz
0 0 1 1 0 976.5625µs 1.024kHz
0 0 1 1 1 1.953125ms 512Hz
0 1 0 0 0 3.90625ms 256Hz
0 1 0 0 1 7.8125ms 128Hz
0 1 0 1 0 15.625ms 64Hz
0 1 0 1 1 31.25ms 32Hz
0 1 1 0 0 62.5ms 16Hz
0 1 1 0 1 125ms 8Hz
0 1 1 1 0 250ms 4Hz
0 1 1 1 1 500ms 2Hz
1 X X X X * 32.768kHz
*RS3–RS0 determine periodic interrupt rates as listed for E32K=0.