This is a CIR (Consumer IR / Remote Control) capture device built with 74HCxx series logic chips. It allows a computer to do a detailed capture with carrier frequency, on/off durations, and on duration pulse counts.

The circuit works by counting the number of IR pulses in a 139 us period, and then sending that count to the computer using ordinary 115,200 bps async serial data. This method allows the use of an ordinary serial port and standard serial port driver. The low power HC series chips allow the circuit to be powered by the serial port.

A xtal oscillator and 74HC4040 12 stage ripple counter are used to provide two clocks. A 115,200 Hz clock is used to clock the serial data transmission, and a 7200 Hz clock is used to set the transmision interval.

A QSE159 IR detector will increment the count in a 74HC4040 counter for each IR pulse. Every 139 us (1 / 7200 Hz) the current count is loaded in to a 74HC165 shift register and sent to the computer as ordinary async serial data.

Software running on the computer converts the running pulse count sent over the serial port to a logic analyzer style display.

Schematic

Prototype on breadboard

PCB

Connection to the computer can be by RS-232 on the DE-9 connector, or by FTDI TTL-232 cable on the 6 pin 100 mil header.

IR Scope software

The carrier frequency is shown at the top left, followed by a sumarry of the first 300 ms.
On and off durations are shown below the trace and the pulse count is shown within the trace at the beginning of each on duration.

Schematic & board files
IR Scope software with source