1
Features
AVR
8-bit RISC Microcontroller with 83 ns Instruction Cycle Time
USB Hub with One Attached and Two External Ports
USB Function with Three Programmable End-points
24 KB Program Memory, 1 KB Data SRAM
32 x 8 General-purpose Working Registers
27 Programmable I/O Port Pins
12-channel 10-bit ADC
Master/Slave SPI Serial Interface
One 8-bit Timer/Counter with Separate Pre-scaler
One 16-bit Timer/Counter with Separate Pre-scaler and Two PWMs
External and Internal Interrupt Sources
Programmable Watchdog Timer
6 MHz Oscillator with On-chip PLL
5V Operation with On-chip 3.3V Power Supply
64-lead LQFP Package
Description
The Atmel AT43USB355 is an 8-bit microcontroller based on the AVR RISC architec-
ture. By executing powerful instructions in a single clock cycle, the AT43USB355
achieves throughputs approaching 12 MIPS. The AVR core combines a rich instruc-
tion set with 32 general-purpose working registers. All 32 registers are directly
connected to the ALU allowing two independent registers to be accessed in one single
instruction executed in one clock cycle. The resulting architecture is more code effi-
cient while achieving throughputs up to ten times faster than conventional CISC
microcontrollers.
Furthermore, the AT43USB355 features an on-chip 24-Kbyte program memory and
1-Kbyte of data memory. It is supported by a standard set of peripherals such as
timer/counter modules, watchdog timer and internal and external interrupt sources.
The major peripheral included in the AT43USB355 is a full-speed USB 2.0 Hub with
an embedded function and a 12-channel Analog-to-Digital Converter (ADC) for use in
applications such as game controllers.
Full-speed
USB
Microcontroller
with Embedded
Hub, ADC and
PWM
AT43USB355
Rev. 2603DUSB2/03
4
AT43USB355
2603DUSB2/03
Signal Description
Name
Type
Function
V
CC1
,
2
,
3
Power Supply/Ground
5V Digital Power Supply
V
CCA
Power Supply/Ground
5V Power Supply for the ADC
V
SS1
,
2
,
3
Power
Supply/Ground
Digital Ground
V
SSA
Power Supply/Ground
Ground for the ADC
CEXT1, 2, 3
Power Supply/Ground
External Capacitors for Power Supplies High quality 2.2 F capacitors must
be connected to CEXT1, 2 and 3 for proper operation of the chip.
CEXTA
Power Supply/Ground
External Capacitor for Analog Power Supply A high quality 0.33 F capacitor
must be connected to CEXTA for proper operation of the chip.
XTAL1
Input
Oscillator Input Input to the inverting oscillator amplifier.
XTAL2
Output
Oscillator Output Output of the inverting oscillator amplifier.
LFT
Input
PLL Filter For proper operation of the PLL, this pin should be connected through
a 0.01 F capacitor in parallel with a 100
resistor in series with a 0.1 F capacitor
to ground (VSS). Both capacitors must be high quality ceramic.
DPO
Bi-directional
Upstream Plus USB I/O This pin should be connected to CEXT1 through an
external 1.5 k
.
DMO
Bi-directional
Upstream Minus USB I/O
DP[2,3]
Bi-directional
Downstream Plus USB I/O Each of these pins should be connected to VSS
through an external 15 k
resistor. DP[2,3] and DM[2,3] are the differential signal
pin pairs to connect downstream USB devices.
DM[2,3]
Bi-directional
Downstream Minus USB I/O Each of these pins should be connected to VSS
through an external 15 k
resistor.
PA[0:7]
Bi-directional
Port A[0:7] Bi-directional 8-bit I/O port with 2 mA drive strength and a
programmable pull-up resistor.
PB[0:7]
Bi-directional
Port B[0:7] Bi-directional 8-bit I/O port with 2 mA drive strength and a
programmable pull-up resistor. PB[0,1,4:7] have dual functions as shown below:
Port Pin
Alternate Function
PB0
T0, Timer/Counter0 External Input
PB1
T1, Timer/Counter1 External Input
PB4
SSN, SPI Slave Port Select or SCL, I2C Serial Bus Clock
PB5
MOSI, SPI Slave Port Select Input
PB6
MISO, SPI Master Data In, Slave Data Out
PB7
SCK, SPI Master Clock Out, Slave Clock In
5
AT43USB355
2603DUSB2/03
PD[0:7]
Bi-directional
Port D[0:7] Bi-directional I/O ports with 2 mA drive strength and a programmable
pull-up resistor. PortD[2,3,5,6] have dual functions as shown below:
Port Pin
Alternate Function
PD2
INT0, External Interrupt 0
PD3
INT1, External Interrupt 1
PD5
OC1A Timer/Counter1 Output Compare A
PD6
OC1B Timer/Counter1 Output Compare B
PF[1:3]
Bi-directional
Port F[1:3] Bi-directional 3-bit I/O port with 2 mA drive strength and a
programmable pull-up resistor. In the AT43USB355E, PF[1:3] pins have dual
functions as the interface pins to the serial EEPROM. After program memory
downloading is complete, PF3 has a third function as Timer/Counter1 Input
Capture, ICP.
Port Pin
Alternate Function
PF1
SCK, SPI Master Clock Out
PF2
MOSI, SPI Slave Data Input
PF3
MISO, SPI Slave Data Out. ICP after download complete
SSN/NC
Output
Slave Select In the AT43USB355E, this pin enables the external serial memory.
In the AT43USB355M, this pin has no function and can be left floating or connected
to VCEXT.
ADC[0:11]
Input
ADC Input[0:11] 12-bit input pins for the ADC.
AREF
Input
Analog Reference Input for the ADC.
TEST
Input
Test Pin This pin should be tied to ground.
RESETN
Input
Reset Active Low.
Signal Description (Continued)
Name
Type
Function
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