| ??? 05/18/06 08:38 Modified: 05/18/06 08:47 Read: times |
#116474 - the smarter monitors work like this Responding to: ???'s previous message |
Erik Malund said:
I do realize that such a scheme would require flash writes but, when no money is available for a real tool, what is most important? the non-interference (i.e. true emulation) of the tool or the speed of using it. Since, with modern chips, your code is likely to run on internal memory, this scheme allows implementation without external memory, thus all 32 pins available. Of course you will need internal RAM available, the size of a flash page and a few other things, but the scheme is feasible and the processor, when not breakpointed would run TRUE.
So, what is the 'cost'? you will never be able to use the top (2k?) of code memory. Also some ERAM, the size of a flash page (512?), must be unused. This is exactly how the smarter monitors do work; except they don't bother to have a 2-byte "breakpointing" (using the interrupt-triggering trick you mention), instead they simply use a 3-byte longjump into the monitor. There is also need for some extra RAM to store variables of the monitor itself and to preserve registers the monitor wants to use. However, as RAM is a valuable article in these chips, there are tricks how to avoid or replace it. For example, Atmel's RD2's do have this extra RAM hidden for the user, so from the user point of view you have a true one-byte write into FLASH as if it would be EEPROM. Philip's P89V51RD2 (+SST's equivalent) has an extra 8k FLASH ("boot FLASH") where the "built-in" monitor core ("SoftICE") is located and the trick is, that it simply stores the ERAM into FLASH while the monitor runs. Jan Waclawek PS. As per fancy VT52-ish interface etc. - OK, I shut up. PS2. I believe you have seen our Webmaster's masterpiece, the 8052.com SBC's monitor. |
| Topic | Author | Date |
| amon52 (work in progress) | 01/01/70 00:00 | |
| v0.4 released | 01/01/70 00:00 | |
| implementing breakpoints | 01/01/70 00:00 | |
| breakpoints in monitors | 01/01/70 00:00 | |
| breakpoints | 01/01/70 00:00 | |
| more | 01/01/70 00:00 | |
| good idea with the EI0 | 01/01/70 00:00 | |
| no and yes | 01/01/70 00:00 | |
| why not for rapid prototyping? | 01/01/70 00:00 | |
| how would you prototype something that | 01/01/70 00:00 | |
| I agree | 01/01/70 00:00 | |
| the smarter monitors work like this | 01/01/70 00:00 | |
| not quite as smart | 01/01/70 00:00 | |
| yep | 01/01/70 00:00 | |
SBC monitor? | 01/01/70 00:00 | |
| do you want a REAL challenge? | 01/01/70 00:00 | |
| It's enough of a challenge | 01/01/70 00:00 | |
| I agree | 01/01/70 00:00 | |
| monitors ... have a look here ... | 01/01/70 00:00 | |
| cheers | 01/01/70 00:00 |