EVAL-ADUC842QSZ Analog Devices Inc, EVAL-ADUC842QSZ Datasheet - Page 57

• Manufacturer Part Number: EVAL-ADUC842QSZ
• Description: Analog MCU Evaluation Board
• Manufacturer: Analog Devices Inc
• Series: QuickStart™ Kitr
• Type: MCUr

Specifications of EVAL-ADUC842QSZ

• Silicon Manufacturer: Analog Devices
• Core Architecture: 8052
• Silicon Core Number: ADuC842
• Tool / Board Applications: General Purpose MCU, MPU, DSP, DSC
• Mcu Supported Families: ADUC8xx
• Contents: Evaluation Board, Power Supply, Cable, Software and Documentation
• Development Tool Type: Hardware - Eval/Demo Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ADuC824
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

8052 COMPATIBLE ON-CHIP PERIPHERALS
This section gives a brief overview of the various secondary
peripheral circuits that are also available to the user on-chip.
These remaining functions are mostly 8052 compatible (with a
few additional features) and are controlled via standard 8052
SFR bit definitions.
Parallel I/O
The ADuC841/ADuC842/ADuC843 use four input/output
ports to exchange data with external devices. In addition to
performing general-purpose I/O, some ports are capable of
external memory operations while others are multiplexed with
alternate functions for the peripheral features on the device. In
general, when a peripheral is enabled, that pin may not be used
as a general-purpose I/O pin.
Port 0
Port 0 is an 8-bit open-drain bidirectional I/O port that is
directly controlled via the Port 0 SFR. Port 0 is also the
multiplexed low order address and data bus during accesses to
external program or data memory.
Figure 57 shows a typical bit latch and I/O buffer for a Port 0
port pin. The bit latch (one bit in the port’s SFR) is represented
as a Type D flip-flop, which clocks in a value from the internal
bus in response to a write to latch signal from the CPU. The Q
output of the flip-flop is placed on the internal bus in response
to a read latch signal from the CPU. The level of the port pin
itself is placed on the internal bus in response to a read pin
signal from the CPU. Some instructions that read a port activate
the read latch signal, and others activate the read pin signal. See
the Read-Modify-Write Instructions section for details.
As shown in Figure 57, the output drivers of Port 0 pins are
switchable to an internal ADDR and ADDR/DATA bus by an
internal control signal for use in external memory accesses.
During external memory accesses, the P0 SFR has 1s written to
it, i.e., all of its bit latches become 1. When accessing external
memory, the control signal in Figure 57 goes high, enabling
push-pull operation of the output pin from the internal address
or data bus (ADDR/DATA line). Therefore, no external pull-ups
are required on Port 0 for it to access external memory.
INTERNAL
TO LATCH
LATCH
WRITE
READ
READ
BUS
PIN
Figure 57. Port 0 Bit Latch and I/O Buffer
LATCH
CL
D
Q
Q
ADDR/DATA
CONTROL
DV
DD
P0.x
PIN
Rev. 0 | Page 57 of 88
In general-purpose I/O port mode, Port 0 pins that have 1s writ-
ten to them via the Port 0 SFR are configured as open-drain and
will therefore float. In this state, Port 0 pins can be used as high
impedance inputs. This is represented in Figure 57 by the NAND
gate whose output remains high as long as the control signal is
low, thereby disabling the top FET. External pull-up resistors are
therefore required when Port 0 pins are used as general-purpose
outputs. Port 0 pins with 0s written to them drive a logic low
output voltage (V
Port 1
Port 1 is also an 8-bit port directly controlled via the P1 SFR.
Port 1 digital output capability is not supported on this device.
Port 1 pins can be configured as digital inputs or analog inputs.
By (power-on) default, these pins are configured as analog
inputs, i.e., 1 written in the corresponding Port 1 register bit. To
configure any of these pins as digital inputs, the user should
write a 0 to these port bits to configure the corresponding pin as
a high impedance digital input. These pins also have various
secondary functions as described in Table 25.
Table 25. Port 1 Alternate Pin Functions
Pin No.
P1.0
P1.1
P1.5
Port 2
Port 2 is a bidirectional port with internal pull-up resistors
directly controlled via the P2 SFR. Port 2 also emits the high-
order address bytes during fetches from external program
memory, and middle and high order address bytes during
accesses to the 24-bit external data memory space.
As shown in Figure 59, the output drivers of Port 2 are switch-
able to an internal ADDR and ADDR/DATA bus by an internal
control signal for use in external memory accesses (as for
Port 0). In external memory addressing mode (CONTROL = 1),
the port pins feature push-pull operation controlled by the
internal address bus (ADDR line). However, unlike the P0 SFR
during external memory accesses, the P2 SFR remains unchanged.
INTERNAL
TO LATCH
LATCH
WRITE
READ
READ
BUS
PIN
Figure 58. Port 1 Bit Latch and I/O Buffer
Alternate Function
T2 (Timer/Counter 2 External Input)
T2EX (Timer/Counter 2 Capture/Reload Trigger)
SS (Slave Select for the SPI Interface)
OL
) and are capable of sinking 1.6 mA.
ADuC841/ADuC842/ADuC843
TO ADC
LATCH
CL
D
Q
Q
P1.x
PIN