Skip to content

{ Category Archives } kit building and hardware hacking

The microcontroller human interface

Generally, anytime I see a little box with a 2 line by 16 or 20 character display and a few buttons and whatnot, I think microcontroller. An example is the West Mountain Radio Target Tuner designed to assist in tuning mobile screwdriver antennas. Sometimes the display is a small OLED graphical display – I’ve seen Ardutesters […]

Garage door openers

The door got halfway up and then there was an unpleasant sound. A bit of a push got it up far enough to get the car out.  A garage door opener is just an example of the robotics exercises except that is has a long history and runs a motor a bit more potent than […]

PICAXE Clock Exercise: the problem of time

Computerphile on YouTube has a good video on The Problem with Time & Timezones. If you want a clock that will be portable in both time and place, you have a very interesting time keeping problem.

PICAXE clock exercise: backwards compatibility creates confusion for interrupts and touch

Exploring two advanced concepts, interrupts and touch input, highlighted errors and confusion in Revolution’s PICAXE documentation. In both cases, newer mcu’s have added features that provide interesting capability yet Revolution hasn’t done a very good job in updating PICAXE or its documentation. They don’t make it clear what commands are being superceded; they enhance commands […]

In circuit capacitor ESR meter and op amp exercise

QST April 2014 has an article on building an ESR meter. One of the sources with a good explanation of the how and why is by kakopa who has a horrifying story about his denial of entry to the U.S. on a trip to visit an ailing aunt (read and weep for the state of […]

PICAXE Clock Exercise: DST issues

It’s the second Sunday in March so a lot of folks have had to adjust their clock for daylight savings time. The clocks that pick up the WWVB radio signals often auto adjust but the manually set clocks like many alarm clocks and clocks in thermostats need to be reset manually. Since the clock chip […]

PICAXE Clock Exercise: Day of Week

The day of the week is the one item in the clock that can be calculated from the date, month, and year. The DS1307 provides a day of week index that increments at midnight and rolls over from 7 to 1. The datasheet indicates that it is up to the clock user to figure out […]

PICAXE Clock Exercise: I2C communications with selective display updating

The Revolution Education folks have done a nice job of building the microcontroller interface library into their boot loader to make the PICAXE. The I2C communications provide an example. This is the core of the code needed to pull time from a DS1307 clock chip via I2C and put it on a display at a […]

PICAXE Clock Exercise: LCD driver

The LCD driver is standard stuff for a 4 bit parallel data feed to an LCD display. A complication is the mapping between the PICAXE 401 and Arduino shield compatibility. That requires the data pins to be addresses independently. There is also a hassle in the PICAXE nomenclature and how it differs for various operations […]

PICAXE clock exercise: hardware

A clock can get rather complex! The idea with this one was to see how the I2C works. I picked up a $5 board on E-Bay with a DS1307 clock, and 24c32 EEPROM, and an optional temperature sensor that all communicates via I2C. You can see it near the bottom of the picture here with […]