AT43USB325E-AU Atmel, AT43USB325E-AU Datasheet - Page 11

• Manufacturer Part Number: AT43USB325E-AU
• Description: IC USB KEYBOARD CTRLR 64LQFP
• Manufacturer: Atmel
• Series: AVR®r

Specifications of AT43USB325E-AU

• Applications: Keyboard Controller
• Core Processor: AVR
• Program Memory Type: SRAM (16 kB)
• Controller Series: AT43USB
• Ram Size: 512 x 8
• Interface: SPI, 3-Wire Serial
• Number Of I /o: 42
• Voltage - Supply: 4.4 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3.4
3.4.1
3355C–USB–4/05
SPI Serial EEPROM Interface (AT43USB325E Only)
Read Sequence
between the two versions is with respect to the serial EEPROM interface pins, GPIO PF[0:3].
The differences are:
The AT43USB325E is designed to interface directly with a synchronous serial peripheral inter-
face (SPI) SEEPROM such as the Atmel AT25HP256/512. All instructions, addresses and data
are transferred with the MSB first and start with a high-to-low SSN transition.
Note:
Figure 3-1.
Figure 3-2.
Port F Pins
PF0
PF1, PF2, PF3
1. The AT43USB325E asserts its SSN output pin and outputs a 3 MHz clock at SCK. It
2. The AT43USB325E transmits the READ opcode (= 0000011) through its MOSI, fol-
3. The SEEPROM then shifts out the data through its MISO pin.
4. The AT43USB325E de-asserts SCK and SSN after 16K bytes data read is complete.
continues to activate SCK until the completion of the read process.
lowed by the 16-bit byte address to be read, x0000. Please note that the
AT43USB325E will send a 16-byte address only. SEEPROM with SPI that requires a
24-bit address cannot be used with the AT43USB325E.
The SPI port of the AT43USB325E at PF[0:3] is dedicated for program memory downloading only.
It cannot be accessed by the firmware program.
MOSI
MISO
SSN
SCK
AT43USB325E Read Sequence
READ Timing
AT43USB325E
AT43USB325E
Slave Select Pin – Its output will be asserted (low) during
downloading of firmware and will stay de-asserted (high) after
download is completed.
Functions as serial EEPROM interface signals during
downloading and as GPIO pins after download is completed.
0
INSTRUCTION
1
2
HIGH IMPEDANCE
3
4
5
6
7
15
8
14
MOSI
MISO
BYTE ADDRESS
SSN
SCK
9 10 11 20 21 22 23 24 25 26 27 28 29 30
13
...
3
2
1
0
MSB
7
6
AT25HP256
5
DATA OUT
4
AT43USB325
3
2
1
AT43USB325M
NC (No connect)
GPIO
0
11