Oki JOB60851 user manual Connecting Microcontroller to USB Controller, 1. ML60851C Block Diagram

Chapter 4 Software Development

USB D+

D-

Transceiver /receiver

Protocol engine

DPLL

Oscillator

Status and

control registers

Setup

registers

(8 bytes)

EP0receive

buffer ( 8 bytes)

EP0 trasmit

buffer (8bytes)

EP1 receive/

trasmit double

buffer

(64 bytesx 2)

EP2 receive/

transmit buffer

(64 bytes)

EP3 transmit

buffer (8 bytes)

FIFO

-DMA
Microcontroller	interface

A7-A0 AD7- AD0

INTR/

RD/

WR/

CS/

ALE ADSEL

D15-D8

DREQ

DACK

Figure 4.3.1. ML60851C Block Diagram

Protocol engine operation for a control transfer setup transaction differs from that for all other transactions.

Setup transactions always write the eight bytes in the associated data packet to the setup registers. If this data is received successfully, the protocol engine sends an ACK back to the host. It also sends a setup interrupt to the control microcontroller to request register readout.

Data receive transactions write the data from the USB bus to the specified endpoint's receive buffer if there is room. If this data is received successfully, the protocol engine sends an ACK back to the host. It also sends a data received interrupt for the command to the control microcontroller. If there is no room in the receive buffer or there is an error, the protocol engine sends an NAK back to the host.

Data transmit transactions send a data packet from the specified endpoint's transmit buffer to the USB bus if there one ready. If the host then sends an ACK completing the transaction, the Data transmit transactions send a data packet from the specified endpoint's transmit buffer to the USB bus if there one ready. If the host then sends an ACK completing the transaction, the protocol engine empties the buffer. It also sends a transmit buffer empty interrupt to the control microcontroller to request more data.

4-3-3. Connecting Microcontroller to USB Controller

The ML60851C offers the following configuration options for the microcontroller interface.

(1)Choice, with ADSEL pin, of separate or multiplexed address and data buses

(2)Choice, with register setting under program control, of 8- or 16-bit DMA

The 16-bit data bus is only available when 16-bit DMA is used.

The JOB60851 board uses separate address and data buses, an 8-bit data bus, and no DMA.

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