K60P100M100SF2RM Datasheet, PDF (1553/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Chapter 51 Universal Asynchronous Receiver/Transmitter (UART)
(transmission or reception). Block guard time (BGT) is the minimum allowable time
between the leading edges of two consecutive characters in opposite directions
(transmission then reception or reception then transmission).
The GT and WT counters reset whenever C7816[TTYPE] = 1 or C7816[ISO_7816E] = 0
or a new dataword start bit has been received or transmitted as specified by the counter
descriptions. The CWT, CGT, BWT, BGT counters reset whenever C7816[TTYPE] = 0
or C7816[ISO_7816E] = 0 or a new dataword start bit has been received or transmitted as
specified by the counter descriptions. When C7816[TTYPE] = 1 some of the counter
values require an assumption regarding the first data transferred when the UART first
starts. This assumption is required when the 7816E has been disabled, when transition
from C7816[TTYPE] = 0 to C7816[TTYPE] = 1 or when coming out of reset. In this
case, it is assumed that the previous (non-existent) transfer was a received transfer.
The UART will automatically handle GT, CGT and BGT such that the UART will not
send a packet prior to the corresponding guard time expiring.
Table 51-205. Wait and guard time calculations
Parameter
Wait time (WT)
Character wait time (CWT)
Block wait time (BWT)
Guard time (GT)
Reset value
[ETU]
9600
Not used
Not used
12
Character guard time (CGT)
Not used
C7816[TTYPE] = 0
[ETU]
WI × 960 × GTFD
Not used
Not used
GTN not wqual to 255
12 + GTN
GTN wqual to 255
12
Not used
Block guard time (BGT)
Not used
Not used
C7816[TTYPE] = 1
[ETU]
Not used
11 + 2^CWI
11 + 2^BWI × 960 × GTFD
Not used
GTN not equal to 255
12 + GTN
GTN equal to 255
11
22
51.4.7.5 Baud rate generation
The value in WF7816[GTFD] does not impact the clock frequency. The SBR and BRFD
are used to generate the clock frequency. This clock frequency is used by the UART only
and is not seen by the device (smartcard). The transmitter clocks operates at 1/16 the
frequency of the receive clock so that the receiver is able to sample the received value 16
times during the ETU.
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1553