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MC68HC11

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Scubasteve

New Member
I'm sure there are people familiar with that microcontroller, because it is well known as an introductory device. Please be more specific of your question, unless you were just curious about how many people used it or something?

Steve
 

Spasm

New Member
Hi again.
Sorry for not being specific.
Well...what i needed to know is...
I'm currently trying to find out how to connect an LCD,Keyboard,external memory(EEPROM),transmitter/receiver to the 68hc11 microP. The problem now is that the I/O lines are not sufficient.
Anyone knows how to overcome this problem?
well...one thing for sure..the tx/rx will be connected to the SCI ports...how bout the rest? Well.. i thought of using serial connections but not sure about the compatibility.
anyone knows about any serial LCD & keyboard thats compatible with this microcontroller?

Thanx
 

Scubasteve

New Member
All depends is the answer :)
Modern eeproms use different interfaces, you just need to pick on and see what it requires. How much space do you need on the eeprom? Sometimes there is integrated external memory support, which makes adding memory easy, but i am not sure if that device has it.
Quick search at digikey I can see that there are many I2C, SPI, 2 wire and 1 wire eeproms available. Typically, you will need to code the routines for each protocol, which would be tedious!

As for the LCD, usually 2 X 16 displays require 6 outputs from a micro.. 4 for databits and 2 for RS and enable.

I am not sure about the keyboard, but usually it is a matrix connected and scanned by the micro, but I cannot help at all there.
To tell you the truth, I never hard coded a micro., but I know OF interfacing stuff to it ;P
Hey, I tried :D

Steve
 

Spasm

New Member
Hey..

Well.....4kbits should be enough :D
But is there another way to the connections rather than using serial?A multiplexing chip mebbe?
I'm trying to write messages on the 68hc11...and sent to the other unit....
Anyone can help?
 

mod_critical

New Member
You can also use shift registers to read the keyboard and output information to the display. I did this once to hook up a 16 key matrix keypad and a parallel LCD (a total of 15 pins) to a Basic Stamp using only six pins! I can't remeber what exact registers I used but a lot of them are chainable too, just as long as everything on them is going the same direction (input or output). Anyway when I read the keypad I shifted in the data from the keypad shift register (connected by three pins, DQ, CLK, and RST) simply by pulsing reset, then pulsing clock. Every time I pulsed the clock, DQ would change, high or low, depending on the state of the pin that was relatvie to which pulse I sent out. So if pins 1, 4, and 6 on the shift were on, and the rest off (numbering starting at 1, ending at 8 ), I would get this data from shifting the bits into an integer: 10010100. Then all I had to do for the LCD was to shift OUT the data that I wanted on each pin of the LCD hookup so that the pins were in that state on the register, then I pulsed the LCD's clock. The LCD would read the states of the five pins connected to the register (Four data bits plus one to indicate half byte per clock data mode), then I would shift the next four bits to the resiters and pulse the LDC clock again. Cake! No extra microcontrollers, you just have to mind what direction the bits are going to end up in on the shift (input grabs bit 1 first and output pushes bit 8 first on the ones I used) Anyway, they can slow response time, but I never have had that problem. Give it a whirl for your input and output devices, but I wouldn't recommend memory devices. Best of luck on your project!
 

Spasm

New Member
Hey...
The way you hook up the keyboard is quite interesting...
Actually I intend to hook up around a 40+ matrix (how many pins does this take???) keyboard,lcd,transmitter receveiver and mebbe some extra pins for motor control :roll:
Think the 68hc11 is kinda short in I/O pins to do that...
Still doin research on how to extend to so many ports...anyone out there tried doing this before??? Tried searching but couldnt find any...
Maybe someone can give me some info?

Thanx :D
 

Mosfet

New Member
There is a company called Semtech [www.semtech.com] which sells keyboard interface ICs.
I haven't used them but they bought a company called Usar, whose chip I used to interface the common PC keyboard to any serial port on a microcontroller. I have a 8052 micro with a 4 line LCD that I can program directly typing on a spare IBM keyboard.
Semtech has several keyboard interface chips, maybe one could help you. Regards.
 

mod_critical

New Member
Your matrix will take p = r + c pins, where p is pins and r is rows and c is columns. Anyway so a 40 key matrix could take 14 pins set up as a 10 by 4. There are shift registers available that chain, and you would just need to make sure you have a large enough variable to store the number you shift in.
 

john1

Active Member
Hi,

8 bit by 8 bit would give you a 64 way matrix,
and it might be easier to find chips than a 10 by 4.

John
 

john1

Active Member
Hi Spasm,

I'm still a bit unclear about what you want to do,
but i think that a lot of earlier keyboards were
serial output.

John
 
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