XR28V384

9

REV. 1.0.0

3.3V QUAD LPC UART WITH 128-BYTE FIFO

1.2.1.1

Start Frame

The Start frame indicates begining of the SERIRQ cycle. During this frame the SERIRQ is driven LOW for 4-8

clock cycles. It can be initiated by the host or V384 depending on the mode of operation.

In the Continuous mode, only the host controller initiates the Start frame to update the SERIRQ line

information. The host controller drives the SERIRQ signal low for 4 to 8 clock periods. Upon a reset, the

SERIRQ signal defaults to the Continuous mode for the host controller to initiate the first Start frame.

In the Quiet mode, the Start frame is initiated by the device/host. The V384 drives the SERIRQ signal active

low for one clock to initiate a Start Frame, and then tri-states it immediately. The host controller will then take

over driving SERIRQ signal low in the next clock and will continue driving the SERIRQ low for 3 to 7 clock

periods. This makes the total number of clocks low for 4 to 8 clock periods. After these clocks, the host

controller will drive the SERIRQ high for one clock and then tri-states it.

A Start Frame may not be initiated while SERIRQ is active. The SERIRQ is active between Start and Stop

frames while it is idle between Stop and Start frames.

1.2.1.2

IRQ Frame

Once the start frame has been initiated, all the peripherals must start counting frames based on the rising edge

of the clock (LCLK). Each IRQ Frame is three clocks: Sample phase, Recovery phase, and Turn-around

phase. During the Sample phase, the peripheral drives SERIRQ low if the corresponding IRQ is active. If the

corresponding IRQ is inactive, then SERIRQ will be left tri-stated. During the Recovery phase, the peripheral

device drives the SERIRQ high. During the Turn-around phase, the peripheral device leaves the SERIRQ tri-

stated. The V384 supports IRQ3, IRQ4, IRQ5, IRQ7, IRQ9, IRQ10, and IRQ11.

1

IRQ0

2

2

IRQ1

5

3

SMI#

8

4

IRQ3

11

5

IRQ4

14

6

IRQ5

17

7

IRQ6

20

8

IRQ7

23

9

IRQ8

26

10

IRQ9

29

11

IRQ10

32

12

IRQ11

35

13

IRQ12

38

14

IRQ13

41

15

IRQ14

44

16

IRQ15

47

17

IOCHCK#

50

18

INTA#

53

19

INTB#

56

20

INTC#

59

21

INTD#

62

32:22

Unassigned

95