83Plus:Ports:86

Synopsis

Port Number: 86h

Function: USB Miscellaneous Events

This port reports when various device-level USB events occur.

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 06. On the TI-83 Plus Silver Edition, this port has no effect.

Read Values

Reading from this port also clears it. Remember the value you read, because you can't go back and read it again.

• Bit 0: Possibly set if the bus has been suspended (no activity for some length of time.)
• Bit 1: Unknown; probably related to HNP and/or SRP.
• Bit 2: Set if a bus reset has occurred (both D+ and D? pulled low for some length of time.)
• Bit 3: Unknown.
• Bit 4: Possibly set if a device has been connected (D+, or maybe D?, pulled high for some length of time.)
• Bit 5: This usually indicates that something was unplugged.
• Bit 6: Unknown; probably related to HNP.
• Bit 7: Calculator cannot provide sufficient power. Usually caused by low batteries, although, some devices cause this every time.

Write Values

• No effect

Comments

This port is used to report various bus events, which are not associated with any particular endpoint. Note that this port (probably) only works if port 5B bit 0 is set. Port 8B might also act as a mask for this port (note that that port is normally set to A1h in host mode, and 05h in peripheral mode.)