Advance Information MC68HC908MR16/MC68HC908MR32 — Rev. 4.0
210 Timer Interface A (TIMA) MOTOROLA
Timer Interface A (TIMA)
11.4.4.2 Buffered PWM Signal Generation
Channels 0 and 1 can be linked to form a buffered PWM channel whose
output appears on the PTE4/TCH0A pin. The TIMA channel registers of
the linked pair alternately control the pulse width of the output.
Setting the MS0B bit in TIMA channel 0 status and control register
(TASC0) links channel 0 and channel 1. The TIMA channel 0 registers
initially control the pulse width on the PTE4/TCH0A pin. Writing to the
TIMA channel 1 registers enables the TIMA channel 1 registers to
synchronously control the pulse width at the beginning of the next PWM
period. At each subsequent overflow, the TIMA channel registers
(0 or 1) that control the pulse width are the ones written to last. TASC0
controls and monitors the buffered PWM function, and TIMA channel 1
status and control register (TASC1) is unused . While the MS0B bi t is set,
the channel 1 pin, PTE5/TCH1A, is available as a general-purpose
I/O pin.
Channels 2 and 3 can be linked to form a buffered PWM channel whose
output appears on the PTE6/TCH2A pin. The TIMA channel registers of
the linked pair alternately control the pulse width of the output.
Setting the MS2B bit in TIMA channel 2 status and control register
(TASC2) links channel 2 and channel 3. The TIMA channel 2 registers
initially control the pulse width on the PTE6/TCH2A pin. Writing to the
TIMA channel 3 registers enables the TIMA channel 3 registers to
synchronously control the pulse width at the beginning of the next PWM
period. At each subsequent overflow, the TIMA channel registers
(2 or 3) that control the pulse width are written to last. TASC2 controls
and monitors the buffered PWM function, and TIMA channel 3 status
and control register (TASC3) is unused. While the MS2B bit is set, the
channel 3 pin, PTE7/TCH3A, is available as a general-purpose
I/O pin.
NOTE: In buffered PWM signal generation, do not write new pulse width values
to the currently active channel registers. Writing to the active channel
registers is the same as generating unbuffered PWM signals.