D12350F20IV Renesas Electronics America, D12350F20IV Datasheet - Page 304

• Manufacturer Part Number: D12350F20IV
• Description: IC H8S/2350 MCU 4.5/5.5V 0+K I-T
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2300r

Specifications of D12350F20IV

• Core Processor: H8S/2000
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: SCI, SmartCard
• Peripherals: DMA, POR, PWM, WDT
• Number Of I /o: 87
• Program Memory Type: ROMless
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 128-QFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -

Section 7 DMA Controller (DMAC)
DREQ
DREQ
DREQ
DREQ Pin Falling Edge Activation Timing
Set the DTA bit for the channel for which the DREQ pin is selected to 1.
Figure 7.23 shows an example of DREQ pin falling edge activated normal mode transfer.
DREQ pin sampling is performed every cycle, with the rising edge of the next cycle after the
end of the DMABCR write cycle for setting the transfer enabled state as the starting point.
When the DREQ pin low level is sampled while acceptance by means of the DREQ pin is
possible, the request is held in the DMAC. Then, when activation is initiated in the DMAC, the
request is cleared, and DREQ pin high level sampling for edge detection is started. If DREQ pin
high level sampling has been completed by the time the DMA write cycle ends, acceptance
resumes after the end of the write cycle, DREQ pin low level sampling is performed again, and
this operation is repeated until the transfer ends.
Rev. 3.00 Sep 15, 2006 page 268 of 988
REJ09B0330-0300
Figure 7.23 Example of DREQ
Address bus
DMA control
[1]
[2] [5]
[3] [6]
[4] [7]
Note: In write data buffer mode, bus breaks from [2] to [7] may be hidden, and not visible.
Channel
DREQ
Acceptance after transfer enabling; the DREQ pin low level is sampled on the rising
edge of , and the request is held.
The request is cleared at the next bus break, and activation is started in the DMAC.
Start of DMA cycle; DREQ pin high level sampling on the rising edge of
When the DREQ pin high level has been sampled, acceptance is resumed after the
write cycle is completed.
(As in [1], the DREQ pin low level is sampled on the rising edge of , and the request
is held.)
Idle
Minimum of 2 cycles
[1]
Bus release
Request
[2]
Read
DREQ
DREQ Pin Falling Edge Activated Normal Mode Transfer
DREQ
[3]
Request clear period
Transfer
source
DMA
read
Write
destination
Acceptance resumes
Transfer
DMA
write
Idle
Minimum of 2 cycles
[4]
Request
release
Bus
[5]
Read
[6]
Request clear period
Transfer
DMA
source
read
Write
Acceptance resumes
destination
Transfer
DMA
write
Idle
starts.
[7]
release
Bus