Transmit Threshold Register; Table 25-19 Transmit Threshold Register Description - Motorola DragonBall MC9328MX1 Reference Manual

25.6.11 Transmit Threshold Register

The bit descriptions and settings for the Transmit Threshold Register (XMT_THRESHOLD) are provided
in Table 25-19.
XMT_THRESHOLD
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 25-19. Transmit Threshold Register Description
Name
Reserved Reserved—These bits are reserved and should read 0.
Bits 31–8
XTH Transmit NACK Threshold—Sets the NACK
Bits 7–4 threshold for the transmitter. When the threshold
number set by XTH has been reached for the
current byte being transmitted, the error flag XTE
in the XMT_STATUS register is set. When XTE is
set, the remaining transmissions queued in the
transmit FIFO are aborted and no more
transmissions occur until software clears XTE. To
trigger XTE, a given byte being transmitted must
reach the XTH threshold itself. Transmit NACKs
accumulated on one byte are not carried over to
the next.
TDT Transmit Data Threshold—Sets the threshold value for the Transmit FIFO at which the TDTF bit in
Bits 3–0 the XMT_STATUS register is set. When the number of bytes in the Transmit FIFO is less than or
equal to TDT, TDTF is set.
MOTOROLA
Transmit Threshold 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
SmartCard Interface Module (SIM)
24 23 22 21 20
r r r r r
0 0 0 0 0
0x0000
8 7 6 5 4
XTH
r rw rw rw rw
0 0 0 0 o
0x000
0000 = XTE is not set, retransmission after NACK
reception is disabled
0001 = XTE sets after 1 NACK is received,
0 retransmissions occur.
0010 = XTE sets after 2 NACKs are received,
a maximum of 1 retransmission occurs.
...
1111 = XTE sets after 15 NACKs are received,
a maximum of 14 retransmissions occurs.
Programming Model
Addr
0x00211028
19 18 17 16
r r r r
0 0 0 0
3 2 1 0
TDT
rw rw rw rw
0 0 0 0
Settings
25-35