T89C51RB2 View Datasheet(PDF) - Atmel Corporation
Part Name
Description
Manufacturer
T89C51RB2 Datasheet PDF : 9 Pages
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T89C51RB2/RC2
Table 3. Pin Description for 40/44 pin packages
Mnemonic
VSS
VCC
P0.0-P0.7
Pin Number
DIL
LCC
VQFP44
1.4
20
22
16
40
44
38
39-32 43-36 37-30
P1.0-P1.7
1-8 2-9
40-44
1-3
1
2
40
2
3
41
3
4
42
4
5
43
5
6
44
6
7
1
7
8
2
8
9
3
XTAL1
XTAL2
19
21
15
18
20
14
Type
Name and Function
I Ground: 0V reference
I
Power Supply: This is the power supply voltage for normal, idle and
power-down operation
I/O Port 0: Port 0 is an open-drain, bidirectional I/O port. Port 0 pins that
have 1s written to them float and can be used as high impedance inputs.
Port 0 must be polarized to VCC or VSS in order to prevent any parasitic
current consumption. Port 0 is also the multiplexed low-order address
and data bus during access to external program and data memory. In this
application, it uses strong internal pull-up when emitting 1s. Port 0 also
inputs the code bytes during FLASH programming. External pull-ups are
required during program verification during which P0 outputs the code
bytes.
I/O Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups.
Port 1 pins that have 1s written to them are pulled high by the internal
pull-ups and can be used as inputs. As inputs, Port 1 pins that are
externally pulled low will source current because of the internal pull-
ups. Port 1 also receives the low-order address byte during memory
programming and verification.
Alternate functions for T89C51RB2/RC2 Port 1 include:
I/O P1.0 : Input / Output
I/O T2 (P1.0): Timer/Counter 2 external count input/Clockout
I/O P1.1 : Input / Output
I T2EX : Timer/Counter 2 Reload/Capture/Direction Control
I SS : SPI Slave Select
I/O P1.2 : Input / Output
I ECI : External Clock for the PCA
I/O P1.3: Input / Output
I/O CEX0 : Capture/Compare External I/O for PCA module 0
I/O P1.4 : Input / Output
I/O CEX1 : Capture/Compare External I/O for PCA module 1
I/O P1.5 : Input / Output
I/O CEX2 : Capture/Compare External I/O for PCA module 2
I/O MISO : SPI Master Input Slave Output line
When SPI is is in master mode , MISO receives data from the slave
peripheral. When SPI is in slave mode , MISO outputs data to the master
controller.
I/O P1.6 : Input / Output
I/O CEX3 : Capture/Compare External I/O for PCA module 3
I/O SCK : SPI Serial Clock
SCK outputs clock to the slave peripheral
I/O P1.7 : Input / Output:
I/O CEX4 : Capture/Compare External I/O for PCA module 4
I/O MOSI : SPI Master Output Slave Input line
When SPI is is in master mode , MOSI outputs data to the slave peripheral.
When SPI is in slave mode , MOSI receives data from the master
controller.
I
Crystal 1: Input to the inverting oscillator amplifier and input to the
internal clock generator circuits.
O Crystal 2: Output from the inverting oscillator amplifier
6
Rev. B - 30-Mar-01
Preliminary
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