68hC11 Question

Hi jm,

there are several versions of the 68HC11, with different sizes of RAM and EEPROM. Depending on the specific version, you might find the maximum functionality rather limited without external memory.

The I/O possibilities of the 68HC11 are quite extensive, making it an interesting basis for a robot. It has timers, ADCs, plenty digital IOs, pulse width generators, RS232, etc. You can work around the memory limitations (if applicable) by adding external memory. I took another approach and use the 68HC11 as an IO processor driven from a Psion 5 through the built-in RS232. The Psion provides a convenient, relatively powerful environment for the high-level, non-time-critical part of robot software, has plenty of memory (8MB RAM + compact flash card), and requires very little power.

If you are interested in more details, please let me know. Good luck with your project!

Best regards,

Peter

Thank you. The chip says:

mc68c11e1fn

I don't know if the other numbers on the chip mean anything useful. It is actually on a control board that went to something (don't know what) and has input for power and outputs, but since I don't know what the board is for, I thought would remove the chip and the things that it sits in for something else. I am a beginner if you couldn't tell!

Hi jm,

the "e1" part indicates the specific version of the 68hc11. It has 512 bytes RAM and 512 bytes EEPROM, and all the usual peripherals of the 68hc11. More info is on

of the nice things about the 68hc11 is that you need very little to get going, a crystal, some power supply decoupling caps, and a MAX232 level translator is sufficient to get it going. It has a special boot-mode that accepts data from the serial interface and loads it into memory. A small program exists that can be loaded this way, and that in turn accepts data from the serial interface and programs the EEPROM with it, without the need for additional programmer hardware.

I programmed a small development environment for the 68HC11 that uses the official Motorola/Freescale assembler, any text editor, and has built-in facilities for terminal and a forth-like host programming language. It fits, together with the assembler, text editor, source files, debugger, and eeprom programming software on a single 720k floppy disk, and runs on anything starting from MS DOS 2.11 upwards. Fairly primitive, but sufficient since you will not be developing huge programs in 512 bytes ;-) Let me know if you are interested, I can provide you with the (TP5.5) source for it as well if you like.

Best regards,

Peter

There is always the possibility that it's an OTP chip of course.

BTW, are you sure that there wasn't an 'H' in that part number ?

I couldn't find an exact match on the part number at Motorola's SPS site, but here's the datasheet for the HC11E series microcontrollers (as you say that you are a beginner, I don't know if you have found this yet.):

HTH,

Simon.

One of the nice things about the 68hc11 is that you need very little

Thanks. I got a stupid question. Can I lite an LED with it?

I don't think there are stupid questions. In my book, not asking and blowing up your 68HC11 would be a lot closer to "stupid".

In fact, you can light a LED with the 68HC11 directly, according to the datasheet page 235:

you put a 1kOhm resistor in series. This would probably work best with the small, 3mA type LEDs. The bigger, 20mA types, would be much dimmer with this circuit. If you want to run a larger LED, you could reduce the resistor value, but I would recommend adding a transistor or buffer inbetween, especially if you intend to light more than 1 LED.

Best regards,

Peter

A Google search on this chip will turn up many pages of robotics applications. Here is just one site that you will probably find useful:

Regards, Michael

Just remembered another good one:

regards, Michael

John, I just recently build a board using a bare board and components using a 68HC11. Since then I started a group and a web site related to microcontrollers of all types but I have tons of information on the

68HCxx line. Either at: the web site is under construction but a bunch of the 68hcxx stuff is already out there. Including photos and links to a bunch of microcontroller boards. If instead of trying to build something around that there are single board computers that you can get started with for around $40. It will save you from having to design around it. However there are links to web sites that have basic schematics involving the 68HC11.

Michael