Digi NS9750 - Manual (Page 657)

w w w . d i g i e m b e d d e d . c o m 6 3 3
S e r i a l C o n t r o l M o d u l e : U A R T
D19:00 CT CT 0x00000 Character GAP timer
Defines the required value for the receive character
GAP timer.
Compute the CT value as shown:
CT = (((Timeout * F
CLK
)/4) - 1
where:
F
CLK
= ( x1_sys_osc / M) (see Table 364 for
examples)
Timeout = Appropriate timeout in seconds
Use the following equation to define the recommended
character GAP timeout value:
Timeout = (NumBitGap / DataRate)
where:
NumBitGap = The number of bits in a character
plus any start, stop, or parity bits.
DataRate = Interface data rate in bits per second.
Note: When PLL is bypassed, F
CLK
equals BCLK
which equals x1_sys_osc/8 . In most designs BCLK =
(398.1312Mhz / 8) = 49.7664 Mhz .
Examples:
Timeout=0.1ms ; CT field= 0x004DB
Timeout=1.0ms ; CT field= 0x03098
Timeout=5.0ms ; CT field= 0x0F2FF
The maximum value that can be programmed into the
CT field is
0x7FFFF .
Bits Access Mnemonic Reset Description
Table 375: Serial Channel B/A/C/D Receive Character GAP Timer