ATA5771-DK1 Atmel, ATA5771-DK1 Datasheet - Page 127

• Manufacturer Part Number: ATA5771-DK1
• Description: BOARD XMITTER FOR ATA5771 868MHZ
• Manufacturer: Atmel
• Type: Transmitterr

Specifications of ATA5771-DK1

• Frequency: 868MHz
• Maximum Frequency: 868 MHz
• Supply Voltage (max): 4 V
• Supply Voltage (min): 2 V
• Supply Current: 8.5 mA
• Product: RF Development Tools
• For Use With/related Products: ATA5771
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9137E–RKE–12/10
Figure 4-54. Three-wire Mode, Timing Diagram
The Three-wire mode timing is shown in
reference. One bit is shifted into the USI Shift Register (USIDR) for each of these cycles. The
USCK timing is shown for both external clock modes. In External Clock mode 0 (USICS0 = 0),
DI is sampled at positive edges, and DO is changed (Data Register is shifted by one) at nega-
tive edges. External Clock mode 1 (USICS0 = 1) uses the opposite edges versus mode 0, i.e.,
samples data at negative and changes the output at positive edges. The USI clock modes cor-
responds to the SPI data mode 0 and 1.
Referring to the timing diagram
1. The Slave device and Master device sets up its data output and, depending on the pro-
2. The Master generates a clock pulse by software toggling the USCK line twice (C and
3. Step 2 is repeated eight times for a complete register (byte) transfer.
4. After eight clock pulses (i.e., 16 clock edges) the counter will overflow and indicate that
tocol used, enables its output driver (mark A and B). The output is set up by writing the
data to be transmitted to the Serial Data Register. Enabling of the output is done by
setting the corresponding bit in the port Data Direction Register. Note that point A and
B does not have any specific order, but both must be at least one half USCK cycle
before point C where the data is sampled. This must be done to ensure that the data
setup requirement is satisfied. The 4-bit counter is reset to zero.
D). The bit value on the slave and master’s data input (DI) pin is sampled by the USI on
the first edge (C), and the data output is changed on the opposite edge (D). The 4-bit
counter will count both edges.
the transfer is completed. The data bytes transferred must now be processed before a
new transfer can be initiated. The overflow interrupt will wake up the processor if it is
set to Idle mode. Depending of the protocol used the slave device can now set its out-
put to high impedance.
CYCLE
USCK
USCK
DO
DI
( Reference )
A
B
MSB
MSB
C
1
D
2
6
6
(Figure
3
5
5
4-54), a bus transfer involves the following steps:
Figure
4
4
4
4-54. At the top of the figure is a USCK cycle
Atmel ATA5771/73/74
5
3
3
6
2
2
7
1
1
LSB
LSB
8
E
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