M66596 datasheet(69/133 Pages) RENESAS

69 / 133 page

M66596FP/WG

rev .1.00

2006.3.14

page 67 of 127

3.2.5

BEMP interrupt

The BEMP interruption is generated whichever it has chosen of Host and Peripheral mode. The (1), (2) shows the

conditions under which BEMP interrupts are generated. The cause of a BEMP for the various pipes should be

confirmed using the pertinent bit of the BEMPSTS register. If an interrupt has been disabled using the BEMPE bit of

the INTENB0 register, the interrupt request is set in the pertinent bit of the BEMPSTS register. When all of the bits

of the BEMPSTS register are cleared by softwear, the controller clears the BEMP bit of the INTSTS0 register. If a

pipe is under the conditions such as (1)(a), (1)(b), or (2) bellow, the controller sets “1” to a pertinent bit of the

BEMPSTS

BEMPENB

(1)

When the sending direction (writing to the buffer memory) has been set

When all of the data stored in the buffer memory has been sent

If a double buffer is being used for the buffer memory, however, the following conditions are observed.

(a) A BEMP interrupt is generated if the buffer on one side is empty and sending of data from the buffer on the

opposite side has been completed.

(b) A BEMP interrupt is generated if data consisting of less than eight bytes is being written to the buffer on

one side and sending of data from the buffer on the opposite side has been completed.

(c)

A BEMP interrupt is not generated if data consisting of eight bytes or more is being written to the buffer on

one side and sending of data from the buffer on the opposite side has been completed.

(2) When the receiving direction (reading of the buffer memory) has been set

If the size of the data packet that was received exceeded the maximum packet size

At this point, if the other maximum packet size parameters were set to a value other than “0” ("MXPS≠0"),

the controller sets the PID bit of the pertinent pipe to “STALL”.

Figure 3.15 shows the timing at which BEMP interrupts are generated.

Peripheral device data sending

Peripheral device data

IN Token Packet

OUT Token Packet

ACK Handshake

Data Packet

STALL Handshake

Data Packet

USB bus

BEMP interrupt

Figure 3.15 Timing at which BEMP interrupts are generated

M66596 Datasheet(PDF) 69 Page - Renesas Technology Corp