Tag: 68hc11

With a Cherry On The Side – Episode Eight (Meet the Cherries)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Disaster Strikes Well, wouldn't you know it? What a day for my 17-year-old Omnibook laptop to decide that it doesn't want to work anymore! The darned thing will charge the (brand new) laptop battery happily, but refuses to recognise that it is holding any … Continue reading With a Cherry On The Side – Episode Eight (Meet the Cherries)

With a Cherry On The Side – Episode Seven (All the Way to Eleven)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Low-Level Interface Due to the slightly odd (not to mention a little inconvenient) low-level PS/2 keyboard hardware-interface, a little bit of ingenuity may be required: R1 and R2 are the pull-up resistors for the open-drain unidirectional CLK and bidirectional DATA signals. R3 and R4 … Continue reading With a Cherry On The Side – Episode Seven (All the Way to Eleven)

With a Cherry On The Side – Episode Six (the input-capture interrupt fires)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Captures but No Interrupt After the tribulations of the last few days, I decided to change the program to display the value in the IC3 captured-value register (TIC3) - the last value of the free-running 16-bit hardware cycle-counter when the most recent IC3 pin-event … Continue reading With a Cherry On The Side – Episode Six (the input-capture interrupt fires)

With A Cherry on the Side – Episode Five (interrupts don’t happen at the worst possible time)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Following on from the "final solution" plan described in the previous episode, the first step is to try to simulate incoming keyboard-clock interrupts. This can be done by using a pin of the output-only PORTB on the 68hc11 directly connected back to the input-capture … Continue reading With A Cherry on the Side – Episode Five (interrupts don’t happen at the worst possible time)

With A Cherry On The Side – Episode Three (terminal setup and more hardware)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] Get Cracking! So I have the target microcontroller SBC, and have verified it is still working. Today I have been setting up more project equipment. First off, I will need to be able to run my favourite simple command-line 68HC11 cross-assembler to generate loadable … Continue reading With A Cherry On The Side – Episode Three (terminal setup and more hardware)

With A Cherry On The Side – Episode Two (How to run code from non-existent ROM)

[A Project to interface a PS/2 keyboard to a 68hc11 microcontroller] The Case of the Unmissing PROM Last time, I mentioned that there was something a bit unusual about my 68HC11E1 MCU, running the BUFFALO monitor program from on-chip PROM. Well, the issue is that the E1 model 68HC11 isn't supposed to have any on-chip … Continue reading With A Cherry On The Side – Episode Two (How to run code from non-existent ROM)

Small Things Come In Big Packages

During December 2015, Digi-Key Electronics have been running a Christmas Draw; by posting to Twitter or Facebook with an appropriate keyword ("#DigiWish"), you can wish for parts from their catalog, and if you are drawn out of the hat, Digi-Key would gift them to you for no charge and with free delivery. Of course, to … Continue reading Small Things Come In Big Packages

Evie Beer: Episode 9 – Doh! and Happy Ending

As we saw last time, I had been having trouble getting meaningful measurements of joystick position using the ADC. It only goes to show few many readers this blog has, because the circuit diagram showed exactly what the problem was, quite clearly, yet no-one commented! And of course all that impedance-limit waffle I spouted last … Continue reading Evie Beer: Episode 9 – Doh! and Happy Ending

Evie Beer: Episode 8 – RTFM!

This time, we're looking at the built-in analogue-to-digital convertor on the 68hc11. In principle, this should be quite easy, but in practice there turned out to be some caveats. First problem was that I had assumed that the breakout connector on the evaluation board SBC had port E wired in the same sequence as ports … Continue reading Evie Beer: Episode 8 – RTFM!

Evie Beer: Episode 7 – It’s A Stick-Up

The Other End Now that RetroChallenge is in the closing week, it is time to take a look at the *other* end of my breakout-board: That thar be a retro "Gameport" socket. I guess that gives a good indication of the next piece of hardware that I am attempting to interface to the 68hc11 SBC... … Continue reading Evie Beer: Episode 7 – It’s A Stick-Up