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surjo_dm said:Thank u crust,
But u wrote,"They usually output an inverted bit stream". What does that mean. Maybe i got it wrong. Can u please xplain me?
Thanks..
Surya![]()
The output are not open collector. They are internally pulled-up by a high value resistor. For SFH505/506 this value is 100k and for all Vishay Telefunken receivers ie. TSOPxxxx series it is 80k.Nigel Goodwin said:The output of the receivers is usually an open-collector output, which means that it requires a pull-up resistor to work. This output is normally switched off, so is pulled high by the pull-up resistor. When it receives a suitable IR modulated signal the output is turned on, pulling the output low. So 'on' is low, and 'off' is high, which is the opposite way to normal convention.
There are some details on IR communication in my PIC tutorials at - they are based on the Sony SIRC remote system.
kinjalgp said:The output are not open collector. They are internally pulled-up by a high value resistor. For SFH505/506 this value is 100k and for all Vishay Telefunken receivers ie. TSOPxxxx series it is 80k.
Nigel Goodwin said:If I get time tonight I'll disconnect the pull-up resistor on one of my IR Boards and see what voltage I get on the output pin (without any connection to any kind of load of course).
kinjalgp said:The receivers in TV uses modulated infrared signal and so it has very high immunity to sunlight or any other ambient IR source. The modulation frequency for most receivers is 38kHz, however it may vary with type of receivers. Check out your receivers specs. The LED should transmit signal at same frequency which a receiver can detect. I think 1kHz is too low and I have never seen any receiver with this carrier frequency.
The output of the receivers is usually an open-collector output, which means that it requires a pull-up resistor to work. This output is normally switched off, so is pulled high by the pull-up resistor. When it receives a suitable IR modulated signal the output is turned on, pulling the output low. So 'on' is low, and 'off' is high, which is the opposite way to normal convention.
There are some details on IR communication in my PIC tutorials at - they are based on the Sony SIRC remote system.