83Plus:Ports:84 - Revision history

Thepenguin77 at 04:18, 28 October 2011

2011-10-28T04:18:24Z

Thepenguin77 at 03:55, 9 December 2010

2010-12-09T03:55:09Z

FloppusMaximus: /* Read Values */ typo

2010-11-12T01:58:49Z

‎Read Values: typo

FloppusMaximus: Port 84: status for port-94 transactions

2010-11-12T01:57:22Z

Port 84: status for port-94 transactions

New page

[[Category:83Plus:Ports:By Address|84 - USB Read-Pipe Events]] [[Category:83Plus:Ports:By Name|USB Read-Pipe Events]]
== Synopsis ==
'''Port Number:''' 84h

'''Function:''' USB Read-Pipe Events

This port reports when a USB transaction on a "read" pipe has finished.

{{84P-Only Port|04}}

=== Read Values ===
'''Reading from this ports also clears it. Remember the value you read, because you can't go back and read it again.'''
* Bit 0: Always 0.
* Bit 1: Set if a read transaction has finished on pipe 1.
* Bit 2: Set if a read transaction has finished on pipe 2.
* Bit 3: Set if a read transaction has finished on pipe 3.
* Bit 4: Hypothetically, set if a read transaction has finished on pipe 4.
* Bit 5: Hypothetically, set if a read transaction has finished on pipe 5.
* Bit 6: Hypothetically, set if a read transaction has finished on pipe 6.
* Bit 7: Hypothetically, set if a read transaction has finished on pipe 7.

=== Write Values ===
* No effect

== Comments ==
This port is used to report the status of [[83Plus:Ports:94|port-94]] USB transactions. Note that this port only works if [[83Plus:Ports:5B|port 5B]] bit 0 is set. [[83Plus:Ports:Port 89|Port 89]] might also act as a mask for this port.

After you write a command to [[83Plus:Ports:94|port 94]], the USB controller will attempt to perform the appropriate transaction for you. This may, of course, take some time (if the calculator is the host, you must wait for the peripheral to respond; if the calculator is the peripheral, you must wait for the host to ask you to speak.) If the calculator is host and the peripheral doesn't have any data to send (it sends a NAK), the controller will need to re-try the transaction, possibly several times. When the transaction actually finishes, a Z80 interrupt will be generated, and the appropriate bit of this port will be set.

As a host, transactions are considered to have "finished" when the peripheral device has either sent a valid data packet, sent a STALL (indicating an error condition), or failed to reply. Which of these has occurred can be determined from [[83Plus:Ports:94|port 94]] (with [[83Plus:Ports:8E|port 8E]] set appropriately.) [[83Plus:Ports:96|Port 96]] tells you how many data bytes were received.

As a peripheral, transactions are considered to have "finished" when a valid data packet has been received from the host, or possibly also when the host has tried to send a data packet and the calculator has replied with a STALL.

Port-91 transactions (i.e., OUT transactions as host, IN transactions as peripheral, and all control transactions) are associated with [[83Plus:Ports:82|port 82]].

Isochronous transactions haven't been tested, and might behave differently.

@@ Line 1: / Line 1: @@
 [[Category:83Plus:Ports:By Address|84 - USB Read-Pipe Events]] [[Category:83Plus:Ports:By Name|USB Read-Pipe Events]]
 == Synopsis ==
 '''Port Number:''' 84h
@@ Line 6: / Line 7: @@
 This port reports when a USB transaction on a "read" pipe has finished. This port hold the values for ports A1h-A7h. Similar to [[83Plus:Ports:85|port 85]]
 === Read Values ===

@@ Line 5: / Line 5: @@
 '''Function:''' USB Read-Pipe Events
-This port reports when a USB transaction on a "read" pipe has finished.
+This port reports when a USB transaction on a "read" pipe has finished. This port hold the values for ports A1h-A7h. Similar to [[83Plus:Ports:85|port 85]]
 {{84P-Only Port|04}}

@@ Line 10: / Line 10: @@
 === Read Values ===
-'''Reading from this ports also clears it.  Remember the value you read, because you can't go back and read it again.'''
+'''Reading from this port also clears it.  Remember the value you read, because you can't go back and read it again.'''
 * Bit 0: Always 0.
 * Bit 1: Set if a read transaction has finished on pipe 1.