| ??? 01/31/07 19:48 Modified: 01/31/07 19:55 Read: times |
#131833 - there you go again ... Responding to: ???'s previous message |
Erik Malund said:
Richard Erlacher said:
While it's true that, in the unlikely event that the 7-cycle interrupt response time overlaps a stretched cycle, it causes an increase in this response time. However, you clearly said it has no impact on your ... This is NOT about 'me' or 'mine' this is about the very word you use "unlikely event" which is the VERY cause of most 'mysterious' 'very intermittent' 'very rarely showing' bugs. It is, indeed about your example. In the example you gave, it makes no difference. Now you're just back-pedalling once again. The fact is, though you may see the 82C55 as a terrible slowpoke, as you've put it, it would work fine in your application, though it would have a significant impact on your data transfer rate because you're always in the loop impacted by the stretched cycles. I find it odd that not even YOU can come up with an example in which it makes a crucial difference. What is the above other that. What can you not grasp in the above which I now have to repeat for the umpteen time since you eveidently can not grasp it? What I don't understand is why you think that code sequence that transfers your data is "time-critical" in light of the fact that you can stop for a minute or two if necessary if you've handled the receiver code correctly. If you have an interrupt occur between data and clock, or between clock and data, it makes no difference at all. you've not read the 82C55 datasheet (remember the power consumption comment?) re power consumption; the 8255 was outdated before the 'C' was inserted, so my full and complete knowledge of "the 82C55 daasheet" predates the 'C' in 8255. The availability of better soliutions happened before the C was there. So, I'll give you the power consumption. Since you have finally stopped commenting on my spelling, I shall not comment on your (rare) case. (yeah .. I noticed that ... I assume you mean the missing 't')So you haven't read the 82C55 datasheet. Why comment on it then? The CMOS part replaced the NMOS/HMOS part in the mid-'80's. you haven't a clue what the cycle stretch capability of your favorite MCU does That surprises me, I use it extesively for data flash read. Now since I do not understand it can I send you a code snippet from where I use it for your to fix since you, evidently know it. Now wait a minute ... you've repeatedly said you never, Never, NEVER use an external data bus. and what time-critical means. OH BOY, are you wrong there. Then why give such a poor example of it? Erik |
