Difference between revisions of "83Plus:Ports:8C"
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(Ports 8C-8D: frame counter) |
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[[Category:83Plus:Ports:By Address|8C-8D - USB Frame Counter]] [[Category:83Plus:Ports:By Name|USB Frame Counter]] | [[Category:83Plus:Ports:By Address|8C-8D - USB Frame Counter]] [[Category:83Plus:Ports:By Name|USB Frame Counter]] | ||
| + | {{84P-Only Port|04}} | ||
== Synopsis == | == Synopsis == | ||
'''Port Number:''' 8Ch (LSB), 8Dh (MSB) | '''Port Number:''' 8Ch (LSB), 8Dh (MSB) | ||
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These ports show the current value of the USB frame counter. | These ports show the current value of the USB frame counter. | ||
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=== Read Values === | === Read Values === | ||
Revision as of 20:22, 27 October 2011
| This port only exists on the the TI-84 Plus and the TI-84 Plus Silver Edition. On the standard TI-83 Plus, it acts as a shadow of port 04. On the TI-83 Plus Silver Edition, this port has no effect. |
Synopsis
Port Number: 8Ch (LSB), 8Dh (MSB)
Function: USB Frame Counter
These ports show the current value of the USB frame counter.
Read Values
- Port 8C: Bits 0-7 of the frame counter.
- Port 8D: Bits 8-10 of the frame counter.
Write Values
- No effect
Comments
These two ports indicate the frame counter value used (presumably) in the most recently sent or received start-of-frame packet. (In normal operation, SOFs are sent by the host, once per millisecond, and contain an 11-bit counter value.) These ports can be used for timing, or simply as an indication that USB is working (since the USB controller will not generate SOFs unless a device is connected.)
