ADUC834 Analog Devices, ADUC834 Datasheet - Page 12

• Manufacturer Part Number: ADUC834
• Description: Precision Analog Microcontroller: 1MIPS 8052 MCU + 62kB Flash + 16/24-Bit ADC + 12-Bit DAC
• Manufacturer: Analog Devices

Specifications of ADUC834

• Mcu Core: 8052
• Mcu Speed (mips): 1
• Sram (bytes): 2304Bytes
• Gpio Pins: 34
• Adc # Channels: 4
• Other: PWM

ADuC834
Pin No. Pin No.
52-Lead 56-Lead
MQFP
28–31
36–39
32
33
40
41
42
43–46
49–52
*I = Input, O = Output, S = Supply.
CSP
30–33
39–42
34
35
43
44
45
46–49
52–55
P2.0–P2.7
P0.0–P0.7
(AD0–AD3)
Mnemonic
(A8–A15)
(A16–A23)
XTAL1
XTAL2
EA
PSEN
ALE
(AD4–AD7)
I/O
I/O
Type* Description
I
O
I/O
O
O
PIN FUNCTION DESCRIPTIONS (continued)
Port 2 is a bidirectional port with internal pull-up resistors. Port 2 pins that have 1s
written to them are pulled high by the internal pull-up resistors, and in that state can
be used as inputs. As inputs, Port 2 pins being pulled externally low will source current
because of the internal pull-up resistors.
Port 2 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.
Input to the Crystal Oscillator Inverter
Output from the Crystal Oscillator Inverter. (See “Hardware Design Considerations”
for description.)
External Access Enable, Logic Input. When held high, this input enables the device
to fetch code from internal program memory locations 0000h to F7FFh. When held
low, this input enables the device to fetch all instructions from external program
memory. To determine the mode of code execution, i.e., internal or external, the
EA pin is sampled at the end of an external RESET assertion or as part of a device
power cycle. EA may also be used as an external emulation I/O pin, and therefore
the voltage level at this pin must not be changed during normal mode operation
as it may cause an emulation interrupt that will halt code execution.
Program Store Enable, Logic Output. This output is a control signal that enables
the external program memory to the bus during external fetch operations. It is
active every six oscillator periods except during external data memory accesses.
This pin remains high during internal program execution.
PSEN can also be used to enable serial download mode when pulled low through a
resistor at the end of an external RESET assertion or as part of a device power cycle.
Address Latch Enable, Logic Output. This output is used to latch the low byte (and
page byte for 24-bit data address space accesses) of the address to external memory
during external code or data memory access cycles. It is activated every six oscillator
periods except during an external data memory access. It can be disabled by setting
the PCON.4 bit in the PCON SFR.
P0.0–P0.7, these pins are part of Port0, which is an 8-bit, open-drain, bidirectional
I/O port. Port 0 pins that have 1s written to them float and in that state can be used
as high impedance inputs. An external pull-up resistor will be required on P0 outputs
to force a valid logic high level externally. Port 0 is also the multiplexed low-order
address and databus during accesses to external program or data memory. In this
application, it uses strong internal pull-ups when emitting 1s.
–12–
REV. A