recommend me a microcontroller

[mstechca]

I have been working with the AT89C2051 for a while, but the problem with it is that the memory is limited, and it requires special logic functions to program it.

What I would like to do is store the code on the ROM chip, so that when it is connected to the microcontroller, the microcontroller executes the code on the rom chip starting at address 0 (beginning of the chip).

I don't want a chip that shares an address and data line together like the intel 8088.

The 8051 chips seem to be more my style, but I need advice.

So to sum up, this is what I want to achieve:

#1. Transfer code from my computer to the ROM chip
#2. Connect the ROM chip to a microcontroller
#3. Connect the HD47780 compatible LCD to the microcontroller's output pins
#4. Run ROM code when circuit is turned on.

I'm looking for a low-cost microcontroller that satisfies this.

 

[Nigel Goodwin]

Your 'connect ROM to controller' scenario ISN'T a micro-controller, it's a micro-processor - a micro-controller has all this internally.

But your list of requirements is incredibly vague, what are you trying to do?.

For a simple micro-controller design, the popular MicroChip PIC series are hard to beat!.

 

[mstechca]

Your 'connect ROM to controller' scenario ISN'T a micro-controller, it's a micro-processor - a micro-controller has all this internally.

thanks for understanding, I realized after I said microcontroller instead of microprocessor.

But your list of requirements is incredibly vague, what are you trying to do?.

I want to be able to make my own miniature computer that has ROM which can be changed without changing the microprocessor.

Once I have the right chip, I will eventually make my own packet radio modem, and connect it to my superregen :wink:

Even though my superregen is not optimized for TV signals, it is definitely optimized to pick up my transmitter signal, even though both units are using cheap $1 batteries from Dollarama (a canadian dollar store).

The reason why I want this rom to microprocessor setup is because I want to make the TNC that interfaces between the computer and the radio. This TNC will work like an ordinary modem.

I also want the microprocessor to be able to send to the computer HTML pages as well, should the connection to the remote station fail. I don't want a disconnect.

It sounds like alot, but you know what I am saying.

so all I need is a chip that:

#1. accepts 8051, or x86 code.
#2. can read from a 16-bit ROM
#3. contains internal ram
#4. has at least 8 output ports
#5. has some input ports

an 8088 almost did the trick, but I didn't want the address and data lines on the same pin.

 

[DirtyLude]

I don't see anything in your description that would justify the need for external memory. You can't create a decoder in 64k?

How do you plan to interface to the computer? If you're sending HTML, I assume a network connection, rather than serial/USB. That means you require ethernet hardware and stack?

If you require TCP/IP, I would suggest the Z8 Acclaim, or the Rabbit Semiconductor chips. I know the Acclaim can handle external memory, I assume the Rabbit does as well.

 

[mstechca]

I don't see anything in your description that would justify the need for external memory. You can't create a decoder in 64k?

I need it because I want the memory to store the HTML pages whenever they need to be loaded.

How do you plan to interface to the computer?

I am using a serial port.

If you're sending HTML, I assume a network connection,

and the network is my computer and my new TNC as soon as I find the right CPU to build it with.

That means you require ethernet hardware and stack?

No, It means I have to know how a hayes compatible modem works.

If you require TCP/IP,

That is done through software. Remember, my TNC must function as a modem. Any operating system should be able to use it.

so I need a rom-less CPU.

 

[Nigel Goodwin]

Your requirements are rather confusing?, but you don't seem to fully understand what a TNC is?.

As you probably know?, a TNC is essentially a radio modem, your telephone modem doesn't store HTML pages in it, why should a radio modem want to?.

As it connects to a computer, use the computer to store and process - if you're building a computer to act as a TNC there seems no point connecting an extra computer to it?.

I also don't see the relevence of HTML with a TNC either?.

 

[Oznog]

I need it because I want the memory to store the HTML pages whenever they need to be loaded.

I am using a serial port.

A uC can store data on an external ROM, no problem. I2C/SPI nonvolatile memory chips are readily available. In fact the common flash memory cards have a SPI interface and thus you can use them too. Those are cheap, huge, and user removable.

A uC can also write data to its ROM, though special conditions apply. The space is of course limited.

The uC can't store code externally. But you don't need to do this from what you describe.

 

[DirtyLude]

Ya, if this isn't program memory and it's just data memory, you have lots of options, like mentioned above, I2C and SPI ROM chips, or even interface a memory card like a MMC card over SPI, then you can have megs of storage.

Still not certain how you are loading these html pages over serial. You would have to have a TCP/IP stack for that. Basicly I have the same questions as Nigel has.

I was trying to build a mini HTML server on a similar chip to a PIC, and managed to interface a SD card as the storage space. Never managed to inteface to the ISA network card, though.

 

[mstechca]

A uC can also write data to its ROM, though special conditions apply. The space is of course limited.

Yes, but the space is way too low.

The uC can't store code externally. But you don't need to do this from what you describe.

I need a CPU to read my ROM chip and treat the ROM contents as if they were instructions. I want a CPU that has separate address/data lines. I don't care about internal ROM.

but you don't seem to fully understand what a TNC is?.
As you probably know?, a TNC is essentially a radio modem,

That is why I'm talking about a TNC, because it closely matches my request.

your telephone modem doesn't store HTML pages in it, why should a radio modem want to?.

The HTML pages are just pretty versions of status and error pages.
I would rather see an HTML page telling me about my error, and giving me options rather than the modem sending the error code, and dial-up networking giving me a super-short error.

if you're building a computer to act as a TNC there seems no point connecting an extra computer to it?.

My "TNC" is more like an enhanced modem. It isn't a fully-featured computer. It processes modem commands and handles them differently than most modems.

 

[diegobin]

Probably the best choice is an "old style" microprocessor that has been ungraded like the RABBIT.
This is based on the old Z80 and keeps a lot of good features like external data and address buses.
The address range has been upgraded from the original 64kB to at least 16MB (as far as I remember).
It should also have a built-in DMA controller.
This gives you a lot of freedom and flexibility compared to traditional microcontrollers.

Furthermore the development tools are very cheap.

Diego

 

[3v0]

I need a CPU to read my ROM chip and treat the ROM contents as if they were instructions. I want a CPU that has separate address/data lines. I don't care about internal ROM.

You have not said anything that supports the need for executing code from external ROM. All I see is "I WANT".

How much ROM do you need?

Why would a memory card not work?

What is your model for updating the code?

If a chip has enough internal flash ROM would a boot loader work ?

 

[Nigel Goodwin]

Please read the dates on posts before replying - this thread is almost 3 years old.