Usage Notes On The 16-Bit Ppg Timer - Fujitsu MB90460 Series Hardware Manual

CHAPTER 13 16-BIT PPG TIMER
13.7

Usage Notes on the 16-bit PPG Timer

Notes on using the 16-bit PPG timer are given below.
■ Usage Notes on the 16-bit PPG Timer
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Notes on using a program for setting
• Write a value to the period setting buffer register (PCSR), duty setting buffer register (PDUT) must be
written after writing to PCSR. Only updating PCSR is prohibited. Be sure to use a word transfer
instruction (MOVW A, dir, etc.) to access PCSR and PDUT.
• Always set the value of duty setting buffer register (PDUT) not greater than period setting buffer
register (PCSR), otherwise the output of PPG is indeterminate.
• Change the CKS2, CKS1 and CKS0 bits of the control status register (PCNTH) when the PPG is
stopped (PCNTH: CNTE=0).
●
Notes about interrupts
• When the IRQF bit of the PPG control status register (PCNTL) is set to "1" and an interrupt request is
enabled (PCNTL: IREN = 1), control cannot be returned from interrupt processing. Always clear the
IRQF bit.
• Since the 16-bit PPG timer shares an interrupt vector with other resource, interrupt causes must be
checked carefully by the interrupt processing routine when interrupts are used.
Also, when EI
276
2
OS is used by the 16-bit PPG timer, shared resource interrupts must be disabled.