Thepenguin77 at 04:25, 28 October 2011

2011-10-28T04:25:28Z

FloppusMaximus: Port 96: number of bytes received

2010-11-15T04:24:54Z

Port 96: number of bytes received

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[[Category:83Plus:Ports:By Address|96 - USB Data-Received Counter]] [[Category:83Plus:Ports:By Name|USB Data-Received Counter]]
== Synopsis ==
'''Port Number:''' 96h (LSB), 97h (MSB, hypothetical)

'''Function:''' USB Data-Received Counter

This port shows the number of bytes left to read from a USB pipe.

{{84P-Only Port|16}}

=== Read Values ===
* Bits 0-7: Number of bytes left to read.

=== Write Values ===
* No effect

== Comments ==
When a data packet has been received - either an IN packet in host mode, or an OUT packet in peripheral mode - the contents of the packet are stored in an internal buffer in the USB controller. Each pipe has its own buffer; this port tells you how many bytes are currently in the queue for the current pipe. (The "current" pipe is determined by [[83Plus:Ports:8E|port 8E]].)

The contents of the buffer can be retrieved using the appropriate [[83Plus:Ports:A0|Ax port]]. As you read bytes from the buffer, port 96 will count down to zero.

Port 97 is probably the MSB; this should be tested. (Note that, for full-speed devices, the maximum size permitted for a single control, bulk, or interrupt data packet is 64 bytes - see sections 5.5 to 5.8 of the USB specification. Isochronous packets may be up to 1023 bytes.)

@@ Line 1: / Line 1: @@
 [[Category:83Plus:Ports:By Address|96 - USB Data-Received Counter]] [[Category:83Plus:Ports:By Name|USB Data-Received Counter]]
 == Synopsis ==
 '''Port Number:''' 96h (LSB), 97h (MSB, hypothetical)
@@ Line 6: / Line 7: @@
 This port shows the number of bytes left to read from a USB pipe.
 === Read Values ===

83Plus:Ports:96 - Revision history

Thepenguin77 at 04:25, 28 October 2011

FloppusMaximus: Port 96: number of bytes received