SEC1210 datasheet(97/218 Pages) MICROCHIP

97 / 218 page

 2013 - 2016 Microchip Technology Inc.

DS00001561C-page 97

SEC1110/SEC1210

The firmware has to clear one of these two bits after having read all the data to allow a new valid packet to be stored in

the corresponding bank.

A NAK handshake is sent by the USB controller only if the banks 0 and 1 have not been released by firmware.

The firmware can reset the hardware pointers by writing a 1 to both BUF0_RDY and BUF1_RDY in a single write.

An endpoint will first be enabled and configured before being able to send bulk or interrupt packets with the PingPong

bit set.

The firmware will fill the data bank 0 with the data to be sent and set the TXRDY (or BUF0_RDY) bit in the USB_EPn_CT-

L_REG (or USB_EPn_BUFRDY_REG) Register to allow the USB controller to send the data stored in data at the next

IN request concerning the endpoint. The firmware can immediately write into the Endpoint 1 data bank. The firmware

can set BUF1_RDY bit when this buffer is ready.

When the IN packet concerning the bank 0 has been sent and acknowledged by the Host, the TXRDY (and BUF0_RDY)

bit is reset by the USB controller. This triggers a USB interrupt if enabled. The firmware will check if the BUF0_RDY bit

is reset before filling the Endpoint 0 Data Bank with new data.

When the IN packet concerning the bank 1 has been sent and acknowledged by the Host, the TXRDY (and BUF1_RDY)

bit is reset by the USB controller. This triggers a USB interrupt if enabled. The firmware will check if the BUF1_RDY bit

is reset before filling the Endpoint 1 Data Bank with new data.

The bank switch is performed by the USB controller after each packet. Until the TXRDY bit has been set by the firmware

for an endpoint bank, the USB controller will answer a NAK handshake for each IN requests concerning this bank.

The firmware will never write more bytes than supported by the endpoint data buffer.

FIGURE 11-6:

BULK/INTERRUPT IN TRANSACTIONS IN PING-PONG MODE

SEC1210 Datasheet(PDF) 97 Page - Microchip Technology