R5F2121AJFP#U0 Renesas Electronics America, R5F2121AJFP#U0 Datasheet - Page 143

• Manufacturer Part Number: R5F2121AJFP#U0
• Description: MCU FLASH 96K 5K CMOS 48-LQFP
• Manufacturer: Renesas Electronics America
• Series: R8C/2x/21r

Specifications of R5F2121AJFP#U0

• Core Processor: R8C
• Core Size: 16/32-Bit
• Speed: 20MHz
• Connectivity: I²C, LIN, SIO, SSU, UART/USART
• Peripherals: POR, Voltage Detect, WDT
• Number Of I /o: 41
• Program Memory Size: 96KB (96K x 8)
• Program Memory Type: FLASH
• Ram Size: 5K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

R8C/20 Group, R8C/21 Group
Rev.2.00 Aug 27, 2008
REJ09B0250-0200
Figure 14.6
The above applies under the following conditions.
Both bits TSTART and TCSTF in the TRACR register are set to 1 (During count).
14.1.1.1
Counter of timer RA
Timer RA has a prescaler and a timer (which counts the prescaler underflows). The prescaler and timer each
consist of a reload register and a counter. When writing to the prescaler or timer, values are written to both the
reload register and counter.
However, values are transferred from the reload register to the counter of the prescaler in synchronization with
the count source. In addition, values are transferred from the reload register to the counter of the timer in
synchronization with prescaler underflows. Therefore, if the prescaler or timer is written to when count
operation is in progress, the counter value is not updated immediately after the WRITE instruction is executed.
Figure 14.6 shows an Operating Example of Timer RA when Counter Value is Rewritten during Count
Operation.
Reloads register of
Reloads register of
timer RA prescaler
timer RA prescaler
IR bit in TRAIC
Count source
Set 01h to the TRAPRE register and 25h to
the TRA register by a program.
Counter of
timer RA
register
Timer Write Control during Count Operation
Operation
Operating Example of Timer RA when Counter Value is Rewritten during Count
0
Page 125 of 458
Previous value
06h
05h
Previous value
The IR bit remains unchanged until underflow is
generated by a new value.
After writing, the reload register is
written to at the first count source.
03h
04h
01h
Reload at
second count
source
00h
After writing, the reload register is
written to at the first underflow.
01h
Reload at
underflow
02h
New value (01h)
00h
Reload at the second underflow
01h
25h
New value (25h)
00h
01h
24h
00h
14. Timers