ATxmega16A4 Atmel Corporation, ATxmega16A4 Datasheet - Page 352

• Manufacturer Part Number: ATxmega16A4
• Manufacturer: Atmel Corporation

Specifications of ATxmega16A4

• Flash (kbytes): 16 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 32 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 34
• Ext Interrupts: 34
• Usb Speed: No
• Usb Interface: No
• Spi: 7
• Twi (i2c): 2
• Uart: 5
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 12
• Adc Resolution (bits): 12
• Adc Speed (ksps): 2000
• Analog Comparators: 2
• Resistive Touch Screen: No
• Dac Channels: 2
• Dac Resolution (bits): 12
• Temp. Sensor: Yes
• Crypto Engine: AES/DES
• Sram (kbytes): 3.3
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: Yes
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.6 to 3.6
• Operating Voltage (vcc): 1.6 to 3.6
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 5
• Output Compare Channels: 16
• Input Capture Channels: 16
• Pwm Channels: 16
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

29.4.6
29.4.6.1
8077H–AVR–12/09
Serial transmission
Status signalling
Figure 29-12. Changing and sampling data
When data transmission is initiated, a data byte is loaded in parallel into the shift register, and
then serialized by shifting the byte out on TDO. The Parity bit is generated and stitched to the
data byte during transmission. The transmission speed is dictated by the TCK signal.
If the PDI is in TX-mode (as a response to an LD-instruction), and a transmission request from
the PDI Controller is pending when the TAP-controller enters the Capture-DR state, valid data
will be parallel-loaded into the shift-register and a correct Parity bit will be generated and trans-
mitted along with the data byte in the Shift-DR state.
If the PDI is in RX-mode when the TAP-controller enters the Capture-DR state, an EMPTY byte
(0xEB) will be parallel-loaded into the shift-register, and the Parity bit will be set (forcing a parity
error) when data is shifted out in the Shift-DR state. This situation occurs during normal PDI
command - and operand reception.
If the PDI is in TX-mode (as a response to an LD-instruction), but no transmission request from
the PDI Controller is yet pending when the TAP-controller enters the Capture-DR state, a
DELAY byte (0xDB) will be parallel-loaded into the shift-register, and the Parity bit will be set
(forcing a parity error) when data is shifted out in the Shift-DR state. This situation occurs during
data transmission if the data to be transmitted is not yet available.
Figure 29-13 on page 352
a response to the repeated indirect LD instruction. However, in this example the device is not
able to return data bytes faster than one valid byte per two transmitted frames, intermediate
DELAY characters are inserted.
Figure 29-13. Date not ready marking
If a DELAY data frame is transmitted as a response to an LD instruction, the programmer should
interpret this as if the JTAG-interface had no data yet ready for transmission in the previous DR-
Capture state. The proper reaction from the programmer is to initiate repeated transfers until a
valid data byte is received. The LD-instruction is defined to return a specified number of valid
frames, not just a number of frames. Hence if the programmer detects a DELAY Character after
transmitting an LD-instruction, the LD-instruction should not be retransmitted, because the first
LD response would still be pending.
Programmer
External
Commands/data
TD I/TDO
TC K
Device
FRAME 0
shows an uninterrupted flow of data frames from the PDI (Device) as
REP
FRAME 1
CNT
S am ple
LD *(ptr)
FRAME 2
0xDB 1
S am ple
FRAME 0
FRAME 1
D0
P 0xDB 1
S am ple
FRAME 2
XMEGA A
FRAME 3
D1
P
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