Tibbit #42 (RTC

The node module for Tibbit #42 (RTC and NVRAM with backup).

Installation Instructions

The module is available as precompiled binary and C source code.

Install the module

npm install @tibbo-tps/tibbit-42

Usage

var rtc = require("@tibbo-tps/tibbit-42").init(socket);

API Methods:

init(socket)

• socked - TPP socket number

Returns an object with the following methods:

.getTime()

Returns an object with the following properties:

• status - status code, 0 if OK
• date - current date and time as JavaScript Date object

.setTime(date)

Writes date and time to RTC where

• date - JavaScript date object

.setSramValue(address, value)

Writes value to SRAM

• address - 0x00..0xFF
• value - 0x00..0xFF Throws exception if address or value is out of range

.getSramValue(address)

Reads value to SRAM

• address - 0x00..0xFF

Returns object with the following properties:

• status - status code, 0 if OK
• value - 0x00..0xFF

Throws exception if address is out of range

Example:

var rtc = require("./tibbit42.js").init("S17");

var before = rtc.getTime();
rtc.setTime(new Date());

var now = rtc.getTime();

console.log(before, now);

About the Tibbit #42 block

This Tibbit is based on the DS3234 IC from Maxim Integrated. This is a temperature-compensated high accuracy RTC with non-volatile memory. Refer to Maxim Integrated datasheet for operation details.

The DS3234 RTC has the -INT/SQW pin, which can be set to trigger at a predefined date/time or output a square wave signal. The -INT/SQW is available to the outside world through the line IO1. -INT/SQW is also accessible from the CPU. The line is multiplexed with the DOUT signal of the DS3234. The multiplexor is controlled by the CS state. When CS is LOW, thus indicating that an SPI transaction is in progress, the multiplexor selects the DOUT line. When CS is HIGH, the multiplexor selects the -INT/SQW signal. Therefore, it is only possible to gauge the -INT/SQW state when the SPI bus is idle.

The Tibbit carries a backup battery which powers the RTC when the main +5V supply is off.