83Plus:Ports:80

Synopsis

Port Number: 80h

Function: USB Device Address

This port controls the current USB device address.

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

Read Values

• Bits 0-6: Current address
• Bit 7: Always 0

Write Values

• Bits 0-6: New USB device address
• Bit 7: Not used

Comments

Since a USB system may have many devices sharing the same data lines, every peripheral device is assigned a unique 7-bit address to identify it. This port is used both to set the calculator's own address (when acting as a peripheral), and to set the address that the calculator is currently "speaking" to (when acting as a host.)

Remember that when you send or receive a Set Address request, the status stage still uses the old address (see section 9.4.6 of the USB specification), so you shouldn't change this port until after the status stage is finished.