M-V850E-IA4 Renesas Electronics America, M-V850E-IA4 Datasheet - Page 376

• Manufacturer Part Number: M-V850E-IA4
• Description: KIT EVAL V850E IA4 UPD70F3186
• Manufacturer: Renesas Electronics America

Specifications of M-V850E-IA4

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

374
(c) Processing of overflow when two or more capture registers are used
Care must be exercised in processing the overflow flag when two or more capture registers are used. First,
an example of incorrect processing is shown below.
The following problem may occur when two pulse widths are measured in the free-running timer mode.
<1> Read the TQ0CCR0 register (setting of the default value of the TIQ00 pin input).
<2> Read the TQ0CCR1 register (setting of the default value of the TIQ01 pin input).
<3> Read the TQ0CCR0 register.
<4> Read the TQ0CCR1 register.
When two or more capture registers are used, and if the overflow flag is cleared to 0 by one capture
register, the other capture register may not obtain the correct pulse width.
Use software when using two or more capture registers. An example of how to use software is shown
below.
Read the overflow flag. If the overflow flag is 1, clear it to 0.
Because the overflow flag is 1, the pulse width can be calculated by (10000H + D
Read the overflow flag. Because the flag is cleared in <3>, 0 is read.
Because the overflow flag is 0, the pulse width can be calculated by (D
Example of incorrect processing when two or more capture registers are used
TQ0CCR0 register
TQ0CCR1 register
INTTQ0OV signal
TIQ00 pin input
TIQ01 pin input
16-bit counter
TQ0OVF bit
TQ0CE bit
FFFFH
0000H
CHAPTER 7 16-BIT TIMER/EVENT COUNTER Q (TMQ)
D
User’s Manual U16543EJ4V0UD
00
<1>
D
10
<2>
D
00
D
D
01
10
<3>
D
11
11
<4>
− D
D
01
10
) (incorrect).
D
11
01
− D
00
).