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allenhuffman
Joined: 17 Jun 2019
Posts: 588
Location: Des Moines, Iowa, USA
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| How much can read/write_program_memory() handle? |
 Posted: Fri Nov 22, 2019 9:02 am |
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For read_program_memory() and write_program_memory() on PIC24 parts:
The help file mentions minimum sizes for reading and writing, but does this CCS function have a maximum size limit? The code I am working to only reads and writes in the minimum size, and I had assumed that was because that's how the API worked. But a quick test seems to let me get an entire "erase size" block (2K on this part, I think).
Any known issues with using larger blocks than the read/write minimum?
(Apologies to the forum admins; I accidentally posted this in the wrong area yesterday.)
_________________
Allen C. Huffman, Sub-Etha Software (est. 1990) http://www.subethasoftware.com
Embedded C, Arduino, MSP430, ESP8266/32, BASIC Stamp and PIC24 programmer.
http://www.whywouldyouwanttodothat.com ?
Using: 24FJ256GA106, 24EP256GP202 and 24FJ64GA002. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19587
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| Posted: Mon Nov 25, 2019 1:33 am |
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Obvious issue is that you then need a large buffer.
The PCD bootloader uses 64byte transfers.
On chips with smaller pages (128byte), this merrily accepts transfers
of KB at a time. |
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allenhuffman
Joined: 17 Jun 2019
Posts: 588
Location: Des Moines, Iowa, USA
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| Posted: Mon Nov 25, 2019 8:20 am |
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| Ttelmah wrote: | Obvious issue is that you then need a large buffer.
The PCD bootloader uses 64byte transfers.
On chips with smaller pages (128byte), this merrily accepts transfers
of KB at a time. |
I am actually trying to find limits on the CCS calls themselves. From tests on one of the PIC24s we use, I was able to do:
| Code: | unsigned int8 buffer[2048];
// fill buffer
write_program_memory (address, buffer, 2048); |
It appeared to do all 2K. I am just wondering if that is handled by CCS for all PIC variations, and I can rely on it, or if I need to split everything up into multiple small read/writes.
_________________
Allen C. Huffman, Sub-Etha Software (est. 1990) http://www.subethasoftware.com
Embedded C, Arduino, MSP430, ESP8266/32, BASIC Stamp and PIC24 programmer.
http://www.whywouldyouwanttodothat.com ?
Using: 24FJ256GA106, 24EP256GP202 and 24FJ64GA002. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19587
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| Posted: Mon Nov 25, 2019 9:12 am |
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I can't see any reason it wouldn't. Internally the count is 16bit. Never
heard of any issue with larger transfers. |
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