Operation Of 8/16-Bit Ppg Timer - Fujitsu MB90335 Series Hardware Manual

CHAPTER 15 8/16-BIT PPG TIMER

15.3 Operation of 8/16-bit PPG Timer

15.3 Operation of 8/16-bit PPG Timer
The 8/16-bit PPG timer has the 4 channels (PPG0, PPG1/PPG2, PPG3) of 8-bit length
PPG unit. Each of them can operate 3-type operations in total, the 8-bit prescaler + 8-bit
PPG modes and the 16-bit PPG mode by performing the direct-coupled (PPG0 + PPG1/
PPG2 + PPG3) operations in addition to the independent mode.
■ Outline of Operation of 8/16-bit PPG Timer
Each of 8-bit length PPG units has two 8-bit-length reload registers for the "L" and "H" sides (PRLL,
PRLH).
Values written in the PRLL and PRLH registers are reloaded to the 8-bit down counter (PCNT) for the "L"
and "H" sides alternately and down-counted at every count clock so that the output pin value is reversed
when the registers are reloaded at the count borrow occurrence. This operation causes the pin output to be
the "L"-width/"H"-width pulse output corresponding to the reload register value.
Operation is started/restarted by the written register bit.
The relation between the reload operation and the pulse output is shown in the following table.
In addition, when the bit4 (PIE0) in PPGC0/PPGC2 is "1" and the bit2 (PIE1) in PPGC1/PPGC3 is "1", the
interrupt request is output at a borrow occurrence from 00
16-bit PPG mode) for respective counter.
■ Operating Mode
The 8/16-bit PPG timer has 3-type operation modes in total, the 2-channel independent mode, the 8-bit
prescaler + 8-bit PPG mode, and the 16-bit PPG mode (MB90335 series have 2 channels for each mode).
The 2-channel independent mode is a mode to allow an independent 2-channel operation as the 8-bit PPG.
The PPG outputs of ch.0 and ch.1 are connected to the PPG0 and PPG1 pins, respectively (PPG2 to PPG3
correspond to ch.2 to ch.3).
The 8-bit prescaler + 8-bit PPG mode is the operation mode to operate the ch.0 (ch.2) as the 8-bit prescaler
and to enable the 8-bit PPG waveform output in an arbiter cycle, by counting the ch.1 (ch.3) at a ch.0 (ch.2)
borrow output. The PPG0 (PPG2) pin is connected to the bit prescaler output of ch.0 (ch.2) and the PPG1
pin is connected to the PPG output of ch.1 (ch.3).
The 16-bit PPG channel mode (MB90335 series provide 2 channels) is the operation mode to allow the
direct-coupling of ch.0 and ch.1 (direct-coupled ch.2, ch.3) to be operated as the 16-bit PPG. Both PPG0
and PPG1 16-bit PPG power outputs are both connected.
352
Reload operation
PRLH → PCNT
FUJITSU MICROELECTRONICS LIMITED
MB90335 Series
Pin output change
PPG0/PPG1 (0 → 1) rising
to FF (borrow from 0000
H H
to FFFF in the
H H
CM44-10137-6E