AT90SCR100 datasheet(215/433 Pages) ATMEL

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TPR0327AY–SMS–30Jan09

AT90SCR100

17.5.13

IN Pipe management

17.5.13.1

“Manual” mode

When the Host requires data from the device, the firmware has to determine first the IN mode to

use using the INMODE bit:

• UPCRX.INMODE = 0. The UPINRQX register is taken in account. The Host controller will

perform (UPINRQX+1) IN requests on the selected Pipe before freezing the Pipe. This mode

avoids to have extra IN requests on a Pipe.

• UPCRX.INMODE = 1. The USB controller will perform infinite IN request until the firmware

freezes the Pipe.

The IN request generation will start when the firmware clear the UPCRX.PFREEZE bit.

Each time the current bank is full, the UPINTX.RXINI and the UPINTX.FIFOCON bits are set.

This triggers an interrupt if the UPIENX.RXINE bit is set. The firmware can acknowledge the

USB interrupt by clearing the UPINTX.RXINI bit. The Firmware reads the data and clears the

UPINTX.FIFOCON bit in order to free the current bank. If the IN Pipeis composed of multiple

banks, clearing the UPINTX.FIFOCON bit will switch to the next bank. The RXINI and FIFOCON

bits are then updated by hardware in accordance with the status of the new bank.

Figure 17-8.

Example of IN Data bank Management

The Pipe must be configured first.

Note

ACK

DATA

(to Bank 0)

UPINTX.RXINI

UPINTX.FIFOCON

Read data from CPU

Bank 0

Read data from CPU

Bank 0

ACK

DATA

(to Bank 0)

Example with 1 IN data bank

ACK

DATA

(to Bank 0)

UPINTX.RXINI

UPINTX.FIFOCON

Read data from CPU

Bank 0

Read data from CPU

Bank 1

ACK

DATA

(to Bank 1)

Example with 2 IN data banks

AT90SCR100 Datasheet(PDF) 215 Page - ATMEL Corporation

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