83Plus:Ports:4A

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 0A. On the TI-83 Plus Silver Edition, this port has no effect.

Synopsis

Port Number: 4A

Function: D− Control

Using this port, you can control the D− USB line. The USB controller doesn't even have to be powered.

Read Values

• Bit 0: Set if 2 and 6 of port 54 are set, 3 of port 4C is set, and VBus is high.
• Bit 1: Set if not connected to computer. Flashes when talking to computer.
• Bit 2: Reset if 2 and 6 of port 54 are set, 3 of port 4C is set, and VBus is high.
• Bit 3: If set, D− is forced high. Max 0.79 mA.
• Bit 4: Only significant if bit 3 is set. If this is set, D− gets extra power. Max total 1.52 mA.
• Bit 5: Reset means D− is getting 0.05 V at 15μA.
• Bit 6: Always 0
• Bit 7: Always 0

Write Values

• Bits 0-2: No effect
• Bit 3: Set to force D− high. Max output: 0.79 mA.
• Bit 4: If bit 3 is set. Setting this give D− extra power. Max total output 1.52 mA.
• Bit 5: Resetting this gives D− 0.05 V at 15μA.
• Bits 6-7: No effect

Comments

If you don't like USB protocol, you could try to use this port for communication, or for sound. Anyways, when you are done, output 20h.