P
Pimpom
- Jan 1, 1970
- 0
Scheme: I have these three different sources of irregular
low-repetition-rate pulses, no two occurring at the same
time, and I want to send them over a long 2-core shielded
cable. I suppose they could be sent as serial data, but my
knowledge of MCUs is limited and dedicated encoder-decoder
pair ICs introduce uncertainty periods of tens of
milliseconds. Such periods can be tolerated but undesireable
if they can be avoided.
I thought I'd found a clever solution by encoding the
signals to 01, 10 and 11 signals and decoding them at the
receiving end with a 2-to-4 line decoder like the CD4555.
Then it occurred to me that slight differences in wire
length and cable and stray capacitances could introduce
different time delays between the two lines and cause
decoding errors. The 11 signal in particular could be
mistaken for a momentary 01 or 10 pulse. Subsequent
controlled stages will not be adversely affected by an
erronous sub-millisecond 01 or 10 pulse at the rising edge
of the 11 signal, but the falling edge could cause problems.
Proposed solution: Have the decoded 11 pulse at the receiver
trigger a monostable. The 11 pulse is a reset signal and
will override the effect of any spurious 01 or 10 signal
during the mono period..
Have I missed anything?
low-repetition-rate pulses, no two occurring at the same
time, and I want to send them over a long 2-core shielded
cable. I suppose they could be sent as serial data, but my
knowledge of MCUs is limited and dedicated encoder-decoder
pair ICs introduce uncertainty periods of tens of
milliseconds. Such periods can be tolerated but undesireable
if they can be avoided.
I thought I'd found a clever solution by encoding the
signals to 01, 10 and 11 signals and decoding them at the
receiving end with a 2-to-4 line decoder like the CD4555.
Then it occurred to me that slight differences in wire
length and cable and stray capacitances could introduce
different time delays between the two lines and cause
decoding errors. The 11 signal in particular could be
mistaken for a momentary 01 or 10 pulse. Subsequent
controlled stages will not be adversely affected by an
erronous sub-millisecond 01 or 10 pulse at the rising edge
of the 11 signal, but the falling edge could cause problems.
Proposed solution: Have the decoded 11 pulse at the receiver
trigger a monostable. The 11 pulse is a reset signal and
will override the effect of any spurious 01 or 10 signal
during the mono period..
Have I missed anything?