Calculators with Support of the 82240 IR-Printer

[Christoph Giesselink]

(08-06-2014 08:15 AM)Martin Hepperle Wrote:  

• A logic zero starts with a half bit pause of 854.5/2 = 427.25 us followed by 8 pulses = 8 / 32768 = 244 us followed by a pause of 427.25 – 244 = 183.25 us. The same interval occurs between the bursts of the three start half-bits. This pause corresponds to 183.25/10^6 * 32768 = 6 cycles. This is a critical value as this pause of 6 cycles should be detectable.
  

I confirm. So it's luck that REDEYE receivers work with the TSOP1833 or TSOP4133.

I made a test equipment for a REDEYE compatible printer many years ago. This printer used the TSOP1833 as receiver. The REDEYE transmitter in the test equipment was crystal driven and always send exactly 7 IR pulses in the half bit frame. I cannot remember any problems with the receiver chip in the printer batch production during the lifetime of this product. So we had luck that we always get batches of TSOP1833 that worked with 7 or less pause pulses.