Endpoint N Fifo Alarm Registers; Table 28-22 Endpoint N Fifo Alarm Registers Description - Motorola DragonBall MC9328MX1 Reference Manual

USB Device Port

28.3.18 Endpoint n FIFO Alarm Registers

The Endpoint n FIFO Alarm Registers define the high/low level alarm setting.
The number of Endpoint n FIFO Alarm Registers in the MC9328MX1 depends on the number of endpoints
configured.
USB_EP0_FALRM
USB_EP1_FALRM
USB_EP2_FALRM
USB_EP3_FALRM
USB_EP4_FALRM
USB_EP5_FALRM
BIT 31 30 29
TYPE r r r
0 0 0
RESET
BIT 15 14 13
TYPE r r r
0 0 0
RESET
Table 28-22. Endpoint n FIFO Alarm Registers Description
Name
Reserved Reserved—These bits are reserved and should read 0.
Bits 31–6
ALRM Alarm Information—Provides the assertion point for the "high level"
Bits 5–0 and "low level" service requests. See the ALARM field of the Endpoint
n FIFO Status Register for more information.
A low level alarm reports lack of data while a high level alarm reports
lack of space. The integrator must decide which alarm is necessary for
each application.
When the amount of data or space in the FIFO is above the indicated
amount, the alarm sets in non-frame mode. In frame mode, the alarm
sets when the amount of data or space in the FIFO is above the
amount indicated by the ALRM setting or when there are end-of-frame
bytes in the FIFO (see frame mode operation).
A "high level" service request is asserted when there are less than
ALRM bytes free in the FIFO. A "low level" service request asserts
when there are less than ALRM bytes of data in the FIFO.
28-32
Endpoint 0 FIFO Alarm Register
Endpoint 1 FIFO Alarm Register
Endpoint 2 FIFO Alarm Register
Endpoint 3 FIFO Alarm Register
Endpoint 4 FIFO Alarm Register
Endpoint 5 FIFO Alarm Register
28 27 26 25
r r r r
0 0 0 0
12 11 10 9
r r r r
0 0 0 0
Description
MC9328MX1 Reference Manual
24 23 22 21 20
r r r r r
0 0 0 0 0
0x0000
8 7 6 5 4
r r r rw rw
0 0 0 0 0
0x0000
Addr
0x00212050
0x00212080
0x002120B0
0x002120E0
0x00212110
0x00212140
19 18 17 16
r r r r
0 0 0 0
3 2 1 0
ALRM
rw rw rw rw
0 0 0 0
Settings
0x00 = 1 data byte left or 1
free byte available
0x01 = 2 data bytes left or 2
free bytes available
...
0x3F = 64 data bytes left or
64 free bytes
available
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