CircuitGizmos

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Re-energizing the ColorMax, Pt. 3

Re-energizing the ColorMax, Pt. 3

Code (BASIC) to control 16 relays

In the earlier parts, we set up the ColorMax (modern design retro computer) to make use of an Arduino relay shield. Now for the BASIC software that will control the start and stop times for 16 relays. The image below is the hardware.

The code starts with mapping the 16 relays to pins on the shield header on the top of the CGCOLORMAX board. Relays 1-4 map to pins 25-28. Other pins are set to 21 until such a time that more relay shields are added. A loop sets all of the defined relay pins to be outputs and then assigns them their initial values.

The relay state array is set up at the beginning of the code with initial values. The relay names are set up in a table. (code could be improved to make these names something that the user could edit.) And default on and off times are set up for the relays.

Some flags and variables are set up before the main code is run. SelectedRelay has the values of 0 to 15 to select the relay for editing, and the odd value of 95 for disabling editing.

SelectStartStop is 0 for editing the start/on times, and 1 for editing the stop/off times.

Following that are flags that tell the software that the user has hit H for incrementing 10s of hours with the H key, 1s of hours for the h key, 10s and 1s of minutes and seconds with the M, m, S, and s keys.

Just before the main loop of code is run, the screen mode is set up, lines drawn on the screen, and then operating key information os printed on the bottom of the screen.

This is the main DO…LOOP for the code. If a key is pressed, a flag is set for processing in a subroutine.

The Update subroutine updates the center part of the display and the Activate subroutine sets the relays on or off.

Update is the routine that displays a line on screen for each of 16 relays. It shows the relay number (indexed starting at 1), the text relay name such as “Kitchen Lamp”, the start/on time, and the end/off time. The line is green if the relay is on, red if it is off.

The time is constantly updated.

When a relay is selected a “>” is located next to the relay name, and next to either the on or off times, depending on which needs to be edited. When relays are not selected or edited, the > disappears.

The bulk of the routine deals with incrementing the right data when a key is pressed.

Relay 3, 4, 11, and 12 are on. (Because they are defaults.)
Relay 6 is being edited. The on time was changed to 3:45:30, and now the off time is being edited.

The Activate subroutine compares current time against the on time and off time. The internal relay state as well as the actual activation output is set to on or off.

The relay is off…


13 seconds ago relay #1 was activated.

And now on…

This example software doesn’t allow for user editing of the relay descriptions and it doesn’t save the times and states. But the SD card is there and that is straight-forward to add. 

The full program:

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Re-energizing the ColorMax, Pt. 2

Re-energizing the ColorMax, Pt. 2

Adding a relay interface shield to the ColorMax

In part 1 it was mentioned that the ColorMax is a great (modern design) retrocomputer for interfacing to the real world. Using the Arduino Shield area on top of the ColorMax, it is easy to interface to a relay module shield. 

Relay Shields

Pictured are two relay shields that I pulled from my collection. They both control 4 relays and they both use the same lines to do so. I had really hoped that they would use different lines so that I could stack them and control 8 (or even 16) relays total. It would have been great if the design of the relay board could have included some option to select other control lines.

The front board uses “D4 through D7” (Arduino nomenclature) to turn the relays on and off. Translating to the ColorMax pin numbers, the control lines are 25, 26, 27, and 28. The “translation” from Arduino numbering to ColorMax numbering is here:  https://circuitgizmos.com/documentation/hardware-datasheets/cgcolormax2-technical-information/cgcolormax2-pin-outs-and-functions/

ColorMax board, bare naked.

So here is my setup for this article. A VGA monitor and a small PS2 keyboard attached to a ColorMax (on an anti-static platform). The Arduino Shield footprint on the ColorMax is populated with headers to accept the Relay Shield. The ColorMax is powered by a 12V supply and connected to a PC via USB.

One Relay Shield in place

With the ColorMax bare naked, the relay board is installed onto the headers. That leaves the relay board ready for control by BASIC.

The simplest way to check out the operation of the relays is to use the immediate mode of basic (and the VGA display with PS2 keyboard) to set the control line direction to output and then write a 1 to turn the relay on and 0 to turn it off. At the basic prompt on the VGA display the first relay (pin 25) can be set to output with this command:

The relay turned on with:

And turned off with:

Next blog: PC control.