Better understanding PULSIN

[flotulopex]

Hello Alain,

This is an example of a 13-bit IR pattern I measure on a TSOP4838 receiver module.
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=2701&stc=1&d=121464754 0">

At the start, my prog captures the incoming pattern sent continiously until it determines the starting-bit (first one after the pause between two patterns) and the number of bits (Bit-Count) in the pattern.

I try with this code:

for Ctr_A = 0 to bit_count
   rctime p_in, 0, h_Bit[Ctr_A]
   rctime p_in, 1, l_Bit[Ctr_A]
next Ctr_A

' Results are:
Bit 00  Low  :13795
    00  High :350
Bit 01  Low  :244
    01  High :1253
Bit 02  Low  :244
    02  High :349
Bit 03  Low  :243
    03  High :350
Bit 04  Low  :244
    04  High :350
Bit 05  Low  :244
    05  High :349
Bit 06  Low  :244
    06  High :349
Bit 07  Low  :243
    07  High :350
Bit 08  Low  :75
    08  High :1
Bit 09  Low  :244
    09  High :650
Bit 10  Low  :243
    10  High :350
Bit 11  Low  :244
    11  High :350
Bit 12  Low  :244
    12  High :349

This is the code (works fine) I use currently use @ 20MHz and the data I get with PULSIN is:

for Ctr_A = 0 to bit_count
   pulsin p_in, 0, L_Bit[Ctr_A]
next Ctr_A
for Ctr_A = 0 to bit_count
   pulsin p_in, 1, H_Bit[Ctr_A]
next Ctr_A

' Resuts are:
Bit 00  Low  :1258 'to be multiplied by 2µs (PULSIN res @ 20MHz)
    00  High :247
Bit 01  Low  :354
    01  High :247
Bit 02  Low  :354
    02  High :247
Bit 03  Low  :355
    03  High :247
Bit 04  Low  :354
    04  High :247
Bit 05  Low  :354
    05  High :247
Bit 06  Low  :354
    06  High :247
Bit 07  Low  :354
    07  High :247
Bit 08  Low  :655
    08  High :247
Bit 09  Low  :354
    09  High :247
Bit 10  Low  :355
    10  High :247
Bit 11  Low  :355
    11  High :247
Bit 12  Low  :354
    12  High :13797

According to your previous message, I might raise the timings accuracy with RCTIME instead of using PULSIN. Unfortunately, I can't get it to work using RCTIME.

What am I doing wrong, please?