Display and control node

Display and control node

The display and control node is the public face of my network. As its name suggests, it displays information from ohter nodes on the network and enables direct interaction with the network nodes through menus and/or the keypad.

The node uses a Picaxe 18X chip, the 18X has more I/O pins and more processing memory than the 08M so it can provide more services -- for example the LCD display and keypad live on this node, as will the DS1307 real-time clock and other I/O devices such as switches and "blinkin' lights."

Features

• 18X running network slave software
• LCD panel for information display.
• Keypad for direct data input.
• LOcally powered -- Displays consume more power than we can reasonably store from the network.
• Implements passive listener processes for capturing and displaying information off the network.

Not implemented yet, but planned for the future:

• DS1307 real-time clock with battery backup to provide the network with time information.
• 24LC256 EEPROMS to store LCD strings and network data.
• Push buttons as required for menu scrolling and selection.
• LED indicators as required for additional "blinkin' lights."

Hardware

The LCD panel is a standard 20X4 LCD with a Hitachi controller. It is hooked up to the 18X with the circuit that Happy Hippy describes on his Web site. The LCD driver subroutines are a mashup between Ron Hackett's drivers from his Nuts & Volts article, Hippy's drivers, and my additions and changes.

The network interface is the one designed by Jurjen for his Serial Power network. I removed the last diode from the circuit (D5), so the interface circuit only provides network data and ground to the display and control node.

Node message table

The display and control node implements handlers for the following message IDs, in addition to the standard slave node message handlers for registering messages and responding to available time slots.