Discussion in "Project Addition or Changes" started by    nitheeshas    Jan 3, 2012.
Tue Jan 03 2012, 09:59 pm
#1
Hey all, I would like to interface the Propeller LED display(discussed in the forum) with a keyboard. The basic idea in my mind is to use a wireless (or wired) connection with the MC (when its not rotating; no need of real-time). I'm thinking of putting it in the following way:

transmitting end:
Keyboard->8051 for interface->encoder-> transmitter

receiving end:
receiver-> decoder -> microcontroller(8051 family)

what about using HT640 & HT648 for encoder & decoder, and RX433 & TX433 for RF receiver & transmitter?

The thing which i dont know about is programming MC at receiving end for saving the character to appropriate memory location, and thats where the problem arises, because i dont know whether 8051 program can access the code memory or not.
Please guys, help me out.
Thu Jan 05 2012, 03:32 pm
#2

what about using HT640 & HT648 for encoder & decoder, and RX433 & TX433 for RF receiver & transmitter?


yes it is better option

because i dont know whether 8051 program can access the code memory or not.


8051 can only access data memory mean RAM
it can't access ROM
Sun Jan 08 2012, 01:43 am
#3
you can modify code to use RAM instead of code memory.. on first boot it reads code memory and moves display data to ram and later on whatever change you make on RAM it will be reflected directly without needing to stop the device which is realtime change.

Its a good innovative idea
Sun Jan 08 2012, 08:49 am
#4
i thought of using a switch on the propeller for displaying & writing a new message..if realtime is possible, then it would be great..
In the programming part for writing the new message, is there any other idea than using an "if-else" type loop for recognizing the character?
Wed Jan 18 2012, 05:14 pm
#5

i thought of using a switch on the propeller for displaying & writing a new message..if realtime is possible, then it would be great..


as i said it is possible... currently code read data from ROM, change it to ram after it runs.. thats it..

i thought of using a switch on the propeller for displaying & writing a new message..if realtime is possible, then it would be great..


I did not get this.. :/ what are you trying to say?
Fri Jan 20 2012, 09:04 pm
#6
In your project code, the message to be displayed is loaded to ram area in that "ramc" segment, right?
so are you saying that i just have to save the new characters to those memory addresses? In your code, its #40h. Isn't that a ram address?
Sat Jan 21 2012, 02:00 am
#7


In your project code, the message to be displayed is loaded to ram area in that "ramc" segment, right?

nitheeshas


"ramc" is a subroutine that moves the message from rom [0x600] to ram [0x40]


so are you saying that i just have to save the new characters to those memory addresses?

nitheeshas


Yes store it at 0x40 in ram.


In your code, its #40h. Isn't that a ram address?

nitheeshas


Yes.

The address does not decide whether it is ram or rom.
There is a address 0x40 in ram and in rom/flash
Sat Jan 21 2012, 08:34 am
#8
@ ExperimenterUK @ nitheeshas
in my point of view that are ROM locations
ORG 40H
means place this code starting at 40h location of program memory
that code can be any user define string or compiler generated code that is called hex file
Sat Jan 21 2012, 03:17 pm
#9
@majoka Phil is talkin about "ramc" subroutine where data from 600H ROM is moved to 40H RAM.
Sun Jan 22 2012, 11:21 am
#10


The address does not decide whether it is ram or rom.
There is a address 0x40 in ram and in rom/flash

ExperimenterUK



so then what determines if its a ram or rom location?

anyways, this is the rough sketch of the code i'm having in mind:

org 0013h
acall input
reti
..
..
..


input:
loop:
mov r0,#40h ;or other ram address
mov a,p3
anl a,#bbh ;clearing P3.2 & P3.6; P3.2 is being used for ext0 interrupt

zero:
cjne a,#00h,one
mov @r0,"0" ;ascii value of zero
ajmp next

one:
cjne a,#01h,two
mov @r0,"1" ;ascii value of one
ajmp next
..
..
..
..

z:
cjne a,#88h,next
mov @r0,"Z" ;ascii value of z
ajmp next

next:
dec r0

cjne a,#ffh,noexit ;ffh is programmed to be the key corresponding to exit the character input sequence
ret


noexit:
ajmp loop

Literally, this is my first program, so i expect a lot of errors..
Please help me to figure them out..

@ajay bro: i saw an additional capacitor in the main circuit pcb in the picture that you have attached in your project, but its not in the circuit..can you pls explain what it is used for?


[ Edited Mon Jan 23 2012, 11:29 pm ]

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