AM29240EH AMD [Advanced Micro Devices], AM29240EH Datasheet - Page 11

• Manufacturer Part Number: AM29240EH
• Description: Enhanced High-Performance RISC Microcontrollers
• Manufacturer: AMD [Advanced Micro Devices]

channel at a time can use either DACKD, DACKC,
DACKB, or DACKA, and the same channel uses the re-
spective DREQD–DREQA signal for transfer requests.
DMA transfers can occur to and from internal peripher-
als independent of these acknowledgments. The
DACKD and DACKC signals are supported on the
Am29240EH and Am29243EH microcontrollers only.
DREQD–DREQA
DMA Request D through A
(input, asynchronous, pull-up resistors)
These inputs request an external transfer on a DMA
channel. DMA requests are not dedicated to a particular
channel—each channel specifies which request line, if
any, it is using. Only one channel at a time can use either
DREQD, DREQC, DREQB, or DREQA. This channel ac-
knowledges a transfer using the respective DACKD–
DACKA signal. These requests are individually program-
mable to be either level- or edge-sensitive for either po-
larity of level or edge. DMA transfers can occur to and
from internal peripherals independent of these requests.
The DMA request/acknowledge pairs DREQA/ DACKA
and DREQB/ DACKB correspond to the Am29200 micro-
controller signals DREQ0/DACK0 and DREQ1/DACK1,
respectively. The pin placement reflects this correspon-
dence, and a processor reset dedicates these request/
acknowledge pairs to DMA channels 0 and 1,
respectively. This permits backward-compatible up-
grade to an Am29200 microcontroller. The DREQD and
DREQC signals are supported on the Am29240EH and
Am29243EH microcontrollers only.
DSRA
Data Set Ready, Port A (output, synchronous)
This indicates to the host that the serial port is ready to
transmit or receive data on Serial Port A.
DTRA
Data Terminal Ready, Port A
(input, asynchronous)
This indicates to the processor that the host is ready to
transmit or receive data on Serial Port A.
GACK
External Memory Grant Acknowledge
(output, synchronous)
This signal indicates to an external device that it has
been granted an access to the processor’s ROM or
DRAM, and that the device should provide an address.
The processor can be placed into a slave configuration
that allows tracing of a master processor. In this configu-
ration, GACK is used to indicate that the processor pipe-
line was held during the previous processor cycle.
Am29240 EH Microcontroller Series
P R E L I M I N A R Y
GREQ
External Memory Grant Request
(input, synchronous, pull-up resistor)
This signal is used by an external device to request an
access to the processor’s ROM or DRAM. To perform
this access, the external device supplies an address to
the ROM controller or DRAM controller.
To support a hardware-development system, GREQ
should be either tied High or held at a high-impedance
state during a processor reset.
ID31–ID0
Instruction/Data Bus (bidirectional, synchronous)
The Instruction/Data Bus (ID Bus) transfers instructions
to, and data to and from the processor.
IDP3–IDP0
Instruction/Data Parity
(bidirectional, synchronous)
If parity checking is enabled by the PCE bit of the
DRAM Control Register, IDP3–IDP0 are parity bits for
the ID Bus during DRAM accesses. IDP3 is the parity
bit for ID31–ID24, IDP2 is the parity bit for ID23–ID16,
and so on. If parity is enabled, the processor drives
IDP3–IDP0 with valid parity during DRAM writes, and
expects IDP3–IDP0 to be driven with valid parity during
DRAM reads. These signals are supported on the
Am29243EH microcontroller only.
INCLK
Input Clock (input)
This is an oscillator input at twice the system operating
frequency.
INTR3–INTR0
Interrupt Requests 3–0
(input, asynchronous, internal pull-up resistors)
These inputs generate prioritized interrupt requests.
The interrupt caused by INTR0 has the highest priority,
and the interrupt caused by INTR3 has the lowest prior-
ity. The interrupt requests are masked in prioritized or-
der by the Interrupt Mask field in the Current Processor
Status Register and are disabled by the DA and DI bits of
the Current Processor Status Register. These signals
have special hardening against metastable states, al-
lowing them to be driven with slow-transition-time
signals.
LSYNC
Line Synchronization (input, asynchronous)
This signal indicates the start of a raster line. This signal
is supported on the Am29240EH and Am29245EH mi-
crocontrollers only.
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