CP3BT23_14 Datasheet, PDF (260/324 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

CP3BT23
SNOSCX3A – JULY 2013 – REVISED JANUARY 2014
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26.1.1 Dual 8-bit PWM Mode
Each timer subsystem may be configured to generate two fully independent PWM waveforms on the
respective TIOx pins. In this mode, the counter COUNTx is split and operates as two independent 8-bit
counters. Each counter increments at the rate determined by the clock prescaler.
Each of the two 8-bit counters may be started and stopped separately using the corresponding TxRUN
bits. Once either of the two 8-bit timers is running, the clock prescaler starts counting. Once the clock
prescaler counter value matches the value of the associated CxPRSC register field, COUNTx is
incremented.
The period of the PWM output waveform is determined by the value of the PERCAPx register. The TIOx
output starts at the default value as programmed in the IOxCTL.PxPOL bit. Once the counter value
reaches the value of the period register PERCAPx, the counter is cleared on the next counter increment.
On the following increment from 00h to 01h, the TIOx output will change to the opposite of the default
value.
The duty cycle of the PWM output waveform is controlled by the DTYCAPx register value. Once the
counter value reaches the value of the duty cycle register DTYCAPx, the PWM output TIOx changes back
to its default value on the next counter increment. Figure 26-2 illustrates this concept.
COUNTx_n
PERCAPx_n
0A
09
08
07
0A
09
08
07
06
06
05
05
DTYCAPx_n
04
03
02
01
04
03
02
01
00
00
TxRUN = 1
TIOn_y (PxPOL = 0)
TIOn_y (PxPOL = 1)
DS354
Figure 26-2. VTU PWM Generation
The period time is determined by the following formula:
PWM Period = (PERCAPx + 1) X (CxPRSC + 1) x T_CLK
(34)
The duty cycle in percent is calculated as follows:
Duty Cycle = (DTYCAPx / (PERCAPx + 1)) × 100
(35)
260 Versatile Timer Unit (VTU)
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