ATMEGA1284PR212-MU Atmel, ATMEGA1284PR212-MU Datasheet - Page 184

• Manufacturer Part Number: ATMEGA1284PR212-MU
• Description: BUNDLE ATMEGA1284P/RF212 QFN
• Manufacturer: Atmel

Specifications of ATMEGA1284PR212-MU

• Frequency: 2.4GHz
• Modulation Or Protocol: 802.15.4 Zigbee, 6LoWPAN, ISM
• Data Interface: PCB, Surface Mount
• Memory Size: 128kB Flash, 4kB EEPROM, 16kB RAM
• Antenna Connector: PCB, Surface Mount
• Package / Case: 44-QFN, 32-QFN
• Processor Series: ATMEGA128x
• Core: AVR8
• Data Bus Width: 8 bit
• Program Memory Type: Flash
• Program Memory Size: 128 KB
• Data Ram Size: 16 KB
• Development Tools By Supplier: ATAVRRZ541, ATAVRRAVEN, ATAVRRZUSBSTICK, ATAVRISP2, ATAVRRZ201
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Supply: -
• Power - Output: -
• Operating Temperature: -
• Applications: -
• Sensitivity: -
• Data Rate - Maximum: -
• Current - Transmitting: -
• Current - Receiving: -
• Lead Free Status / Rohs Status: Details

17.8.6
17.8.7
17.9
17.9.1
8059D–AVR–11/09
Asynchronous Data Reception
Disabling the Receiver
Flushing the Receive Buffer
Asynchronous Clock Recovery
with the received data and stop bits. The Parity Error (UPEn) Flag can then be read by software
to check if the frame had a Parity Error.
The UPEn bit is set if the next character that can be read from the receive buffer had a Parity
Error when received and the Parity Checking was enabled at that point (UPMn1 = 1). This bit is
valid until the receive buffer (UDRn) is read.
In contrast to the Transmitter, disabling of the Receiver will be immediate. Data from ongoing
receptions will therefore be lost. When disabled (i.e., the RXENn is set to zero) the Receiver will
no longer override the normal function of the RxDn port pin. The Receiver buffer FIFO will be
flushed when the Receiver is disabled. Remaining data in the buffer will be lost
The receiver buffer FIFO will be flushed when the Receiver is disabled, i.e., the buffer will be
emptied of its contents. Unread data will be lost. If the buffer has to be flushed during normal
operation, due to for instance an error condition, read the UDRn I/O location until the RXCn Flag
is cleared. The following code example shows how to flush the receive buffer.
Note:
The USART includes a clock recovery and a data recovery unit for handling asynchronous data
reception. The clock recovery logic is used for synchronizing the internally generated baud rate
clock to the incoming asynchronous serial frames at the RxDn pin. The data recovery logic sam-
ples and low pass filters each incoming bit, thereby improving the noise immunity of the
Receiver. The asynchronous reception operational range depends on the accuracy of the inter-
nal baud rate clock, the rate of the incoming frames, and the frame size in number of bits.
The clock recovery logic synchronizes internal clock to the incoming serial frames.
illustrates the sampling process of the start bit of an incoming frame. The sample rate is 16 times
the baud rate for Normal mode, and eight times the baud rate for Double Speed mode. The hor-
izontal arrows illustrate the synchronization variation due to the sampling process. Note the
Assembly Code Example
C Code Example
USART_Flush:
void USART_Flush( void )
{
}
sbis UCSRnA, RXCn
ret
in
rjmp USART_Flush
unsigned char dummy;
while ( UCSRnA & (1<<RXCn) ) dummy = UDRn;
1. See “About Code Examples” on page 6.
r16, UDRn
(1)
(1)
ATmega1284P
Figure 17-5
184