Minicom Connection Over Serial Port To PIC18F452 Device

Robert L Cochran cochranb at speakeasy.net
Fri Apr 7 23:07:08 UTC 2006


Robert L Cochran wrote:

> Mike McCarty wrote:
>
>> Robert L Cochran wrote:
>>
>>> I'm trying to use minicom on Fedora Core 4 to speak to a PIC18F452 
>>> chip which contains a preloaded version of the Microchip TCP/IP 
>>> stack. I built the device myself from a kit; it is intended to be a 
>>> small web server. My objective is to assign an IP address to the 
>>> RTL9019AS ethernet controller. This can be accomplished over a setup 
>>> menu that appears in the minicom window. I suspect I have incorrect 
>>> minicom settings.
>>
>>
>>
>> [snip]
>>
>>> Then I start the setup menu again in a new minicom window. The 
>>> original -- default -- IP address appears.
>>>
>>> So it seems like the option to save the IP address isn't working 
>>> right. Things are apparently lost when I restart the device.
>>>
>>> Is this a minicom software issue, or is it bad soldering on my part 
>>> with the actual device being tested? I'm quite willing to agree it 
>>> may have soldering issues.
>>
>>
>>
>> I don't see how it can be Minicom. All it does is transport
>> characters from your keyboard out the serial port, and from
>> the serial port to your display. If you are getting communications
>> with the device, then Minicom is doing its job. Without knowing
>> more about the PIC device, I can't say any more. Are you using
>> shadow RAM or nonvolatile RAM or EEPROM or FLASH EEPROM or what
>> to store? If it uses a RAM copy, but saves config in a serial
>> EEPROM, it could be that you indeed have a solder problem
>> on the board, like a cold solder joint to the data clock pin.
>>
>> In any case, I don't see how it can be Minicom.
>>
>> Mike
>
>
> Thank you -- I will check my soldering work; I've already looked at 
> the EEPROM (a Microchip 24LC256) and I think I did a poor job on pin 
> 1. Probably the other pins too, this is the first SOIC I've ever 
> soldered.
>
> I also think I need to learn about the different types of RAM and 
> EEPROM you are referencing above. I know i'm using an EEPROM, but I 
> need to learn what shadow or nonvolatile RAM is and how an EEPROM 
> differs from a flah EEPROM.
>
> I'll start looking at datasheets and do some resoldering.
>
> Thanks
>
> Bob
>
My thanks to Peter, Mikkel and Mike for their help with this. I was able 
to get the board working in its web server capacity. Here is what fixed it:

I resoldered the 24LC256 EEPROM chip. That allowed the IP address 
changes to "stick". It also allowed me to upload the website image to 
the EEPROM.

I noticed that the device was plugged into a 100 Mbps-only network hub. 
The Reaktek RTL8019AS is a 10 Mbps chip. Changing to a 10/100 Mbps wired 
router and creating a second, smaller network was the finishing touch. 
Suddenly, I can access the Microchip demonstration website stored on the 
24LC256 chip.

Now to learn how to actually program a PIC microcontroller.

Bob






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