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CHAPTER 20 LIN-UART
20.6.2 Restarting the Reload Counter
The reload counter is a 15-bit reload counter that functions as dedicated baud rate
generator. The transmission/reception clock is generated by the external or internal
clock. Also, the count value of the transmission reload counter can be read by the baud
rate generator register (BGR1, BGR0).
■ Function of Reload Counter
The reload counter has the transmission and reception reload counters and functions as dedicated baud rate
generator. It consists of a 15-bit register for the reload value and generates the transmission/reception
clocks by the external or internal clock. Also, the count value of the transmission reload counter can be
read by the baud rate generator register (BGR1, BGR0)
●
Count start
When the reload value is written to the baud rate generator register (BGR1, BGR0), the reload counter
starts counting.
●
Restart
If the REST bit of the Serial Mode Register (SMR) is set to "1", both Reload Counters are restarted at the
next clock cycle. This feature is intended to use the Transmission Reload Counter as a simple timer.
The following figure illustrates a possible usage of this feature (assume that the reload value is 100.)
Figure 20.6-3 Reload Counter Restart Example
In this example the number of MCU clock cycles (cyc) after REST is then:
cyc = v - c + 1 = 100 - 90 + 1 = 11,
where v is the reload value and c is the read counter value.
MCU
REST
Reload
Value
Read
BGR0/1
Data
Bus
90
: don’t care
Reload
Clock
Counter
Clock
Outputs
37 36 35 100 99 98 97 96 95 94 93 92 91 90 89 88 87