Part 1: Textbook Stuff

NEC Repeat Key down—skip over header pulse NEC read mode Save Address Get 8 bits Read data Verify single pulse Repeat Valid Repeat Save data Valid key 38KHz Pulse Position During first pulse: set up to read 8 bits Read 8 more bits & ignore the inverted address Space <6T? Set repeat flag

JVC 38KHz Measure first pulse (16bit) JVC read mode read space > 8* Threshold ? Read addr & data Read addr Repeat? Read data Same as previous? Valid Repeat Verify /Addr & /Data Valid key no yes

RCA (and Xbox)

Philips RC-6 Leader pulse Normal bits Leader and trailer bits

Panasonic

Daewoo

Sony

Sharp

Philips RC-5

Protocol Summary

Remote Control Recognition (“textbook”) Group 1: includes a large header –NEC – 16:8 mark/space (38KHz) –JVC – 16:8 (38KHz) –RCA – 8:8 (56KHz) –RC-6 – 6:2 (36KHz) –Panasonic – 8:8 (38KHz) –Daewoo – 16:8 (38KHz) Group 2: short header –Sony – 4 (40KHz) Group 3: no header –Sharp (38KHz) –RC-5 (36KHz) Pulse Position Codes –NEC, JVC, RCA, Panasonic, Daewoo, Sharp Manchester –RC-5, RC-6 Pulse width –Sony Set pulse threshold = 5 Max pulse > 5T? Analyze Max pulse > 3T? Sharp Count total pulses until large space Yes: Group 1 NEC Yes Measure shortest pulse (= T) Measure longest & shortest spaces Measure longest pulse Max pulse > 12T Yes Evaluate # of pulses > 12? No RC-5 Sony Max pulse > 7T # of pulses > 20? Yes Determin e if stop bit is used Yes No Daewoo JVC No RC-6 # of pulses > 24? Panasonic RCA/Xbox Yes No Yes No

Part 2: Reality

Findings From Actual Measurements Vendors do not necessarily have unique protocols –Example: Sharp uses NEC plus their own NEC protocol is the “standard” for off-brand remotes –Even name-brands use it for many models Sony is unique—no variants and no one else uses it Several variants of the NEC protocol –Toshiba & Daewoo use NEC with somewhat different timings –JVC uses same header structure but different Addr/Data Sharp is unique RC5 used by many vendors RCA not the same as RC5, as suggested in on-line info Caveat: measurements only done on OLD remotes –Used an X10 UR-19a to generate the signals

Some Measurements

Revised Recognition Logic Group 1: NEC –large header, 32 bit payload Group 2: JVC –large header, 17 bit payload Group 3: Sony –short header, 12 bit payload Group 4: Sharp –no header, 15 bit payload Group 5: RC-5 –no header, 10 bit payload Group 6: RCA –short header, large number of spaces > 2T Group 7: RC-6 –Short header, max # of pulses Pulse Position Codes –NEC, JVC, Sharp, RCA Manchester –RC-5, RC-6 Pulse width –Sony Max pulse >7T? Analyze Max pulse > 3T? Sharp Count total pulses until large space Yes: Group 1& 2 & 6 NEC Yes Measure shortest pulse (= T) Measure longest & shortest spaces Measure longest pulse # of pulses > 30 Yes Evaluate # of pulses > 12? No RC-5 RC-6 # of pulses < 15? JVC Sony RCA/Xbox Yes No No: Groups 3,4,5 and 7 Count total pulses greater than 2T Measure length of header space after break (repeat) # of >2T spaces > 30 No: Groups 1&2 No: Group 4, 5

Remote Control Input Entry: IR receiver routine Read the remote Pulse on? (=‘0’) Return with zero (‘no key’) Yes Valid header? Return with zero (‘no key’) Same as last key? Yes Short delay Return with key variable delay with key up check Valid addr? Return with zero (‘no key’) Yes No Key released? Yes Return with zero (‘no key’); disable repeat for next key Note: this is “as written”, and it works Convert remote key to keycode Timer Interrupt