Unhook a Raspberry Pi from the mains and it forgets the time and date. It’ll only get them back again if you re-connect it to the Internet or enter the data manually. As a Pi user who doesn’t keep his kit connected – I usually wire and power it up when I need it – and doesn’t always bother with the Ethernet cable when he does, I’ve been after a decent real-time clock (RTC) add-on for quite a while. An RTC allows your Pi to keep time, even when the Pi’s power is cut.
When it comes to hacking hardware there’s an easy way and there’s a hard way.
The hard way involves connecting peripherals direct to one of the standard buses supported by your Raspberry Pi, Arduino, Beaglebone or whatever. Buses like I²C, SPI, UART and 1-Wire. You’ll need to take care with your wiring: have you got the right pull-up or pull-down resistor? Is there too much capacitance in the line?
Better late than never. An edited version of this review appeared in The Register in August 2014. I intended to reproduce the original here, but never got round to it. At long last – and a tad late now the Pi 2 is out, of course – here for the record…
You might think that were you a purveyor of a nifty compact computer selling by the millions, you’d consider two years after the debut of your first offering that it was high time you tempted back buyers with a go-faster, more capacious and shinier model. Heck, Apple and others don’t even wait that long: they upgrade products year in, year out.
There is no shortage of clip-on boards designed for the Raspberry Pi, almost all designed to make the tiny computer’s GPIO pins more accessible in order to ease the connection of devices to it, particularly ones that operate at voltages that are not Pi friendly.
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Previously on ‘ZX81: a Raspberry Pi retro restyle’: I used a headerless Arduino Leonardo to connect a ZX81 microcomputer keyboard to a Raspberry Pi via USB, using code to handle normal, shifted and function-shifted key presses.
After some searching on eBay, I found an old ZX81 going cheap because it lacked cables, though when it arrived, I found the computer itself to be in excellent condition. Possibly it has never been used, though how if that were the case the cables were lost and the box got so tatty is a mystery I will probably never solve.Continue reading