Jeethu Rao wrote:
>
> Hi,
>
> I've written a plain vanilla style BootLoader for 16f877.
> It uses the hardware USART and has a code checksumming routine
> like the one Olin had suggested some time back. The porgram words
> in location 0 to 3 are handled smartly like in Wouter's Wloader.
> The commands are all 5 bytes long with a 1 byte checksum appended.

It will depend on your clock speed that the chip is running at.

There will be an absolute minimum time to read ROM based on your
instructions needed to read a ROM location, buffer the data, increment
EEADR/EEADDH, prepare to send, and transmit with acknowledge. Windows
will also slow this process down considerably, and it doesn't seem to
like transfers with large "chunks" of serial data. I usually send 16
byte packets at 19200 baud which seems ok, although I have sent odd ones
at 64 bytes. Larger packet streams seem to lose a byte here and there
especially on older 486's and such. This may be due to the serial
component that I use, but I have to stick with what I know.

ROMzap doesn't read ROM because so far I haven't had a need to do this.
It mainly gets used to program ROM, although it can read RAM and EEPROM
on execution of code break points, which takes a second or two.

Re-programming can be faster than it takes you to release the mouse
button, up to around a minute or so depending on whatever ROMzap decides
needs updating.

I haven't tried it, but I don't think I would have data transfers
controlled by interrupts to try and save a bit of time while
simultaneously reading ROM. This may interfere with the ROM read
procedure as set down in the data sheet.

Maybe cut your command size down. ROMzap uses single byte commands,
although only 3 bits are actually used.

--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
mailto:sales@bubblesoftonline.com

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