How-To: Pentax intervalometer

The inimitable Randy Sarafan writes:

I decided to make a quality DIY intervalometer for my DSLR Pentax camera. This intervalometer should work with most major brands of DSLR cameras such as Nikons and Canons. It works by triggering the shutter using the camera’s remote trigger port. It can also auto-focus before each shot if so desired (or toggle this on or off at any time). The brains of this intervalometer is an Arduino chip. It may seem very complicated at first glance, but is actually a simple circuit and not that hard to make.

BY Becky Stern

Becky Stern is head of wearable electronics at Adafruit Industries. Her personal site: sternlab.org

4 Responses to How-To: Pentax intervalometer

1. jamesBrauer on said:

I just figured out how to parse a hex Pronto IR code into a waveform. So the plan tonight is to just hard code the timing for a Pentax IR remote(that someone else kindly learned with their Pronto remote) into an Arduino, and use it to blink an IR LED to trigger the shutter on my Pentax K110D. Being somewhat lazy on occasion, I will likely just hard code a delay between shots rather than making a nice configurable unit as shown.

• CircuitGizmo on said:

I’ve always had a passing curiosity about the Pronto codes. Are you willing to share what you learned?

• jamesBrauer on said:

Most of what I learned came from http://www.remotecentral.com, but I’ll put my rough notes below.

I got an Arduino sketch working that lets you hand enter the Pronto codes, then toggles a burst out of the pin for the IR led at an interval entered via serial port. It saves the picture snap interval to eeprom for stand-alone use. I’ll try to do a write-up when I get my 2n222 driving the IR LED properly and it completely works.

————– —————

Using pronto irtool, it looks like
a binary one is 0x01ee 0072
a binary zero is 0×0026 0026

1 0 0 0 0 0 0 0

The carrier is 0x006e = 110 cycles or 37.683 kHz
Freq=1000000/(carrier *. 241246)
Rounding some, this is 25micros.

there are 0×0008 burst pairs

0x1ee = 494 * 25u = 12.35ms
0×72 = 114 * 25u = 2.85 ms
0×26 = 38 = 0.95 ms

on off on off on off on off on off on off on off on off
12ms 3ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms 1ms
01EE 0072 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026

format explained
http://www.remotecentral.com/features/irdisp2.htm

Here is the hex:

#
# Converted by AhMan using pronto2rdf utility
#
TITLE=pentax digitalcamera
CROSS=Photo
0000 006E 0008 0000 01EE 0072 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026
CIRCLE=Wide/Mid/Tele
0000 006E 0008 0000 01EE 0072 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0026 0072 0026 0026