ATTIny2313-16MI ATMEL Corporation, ATTIny2313-16MI Datasheet - Page 123

no-image

ATTIny2313-16MI

Manufacturer Part Number
ATTIny2313-16MI
Description
8-bit AVR Microcontroller with 2K Bytes In-System Programmable Flash
Manufacturer
ATMEL Corporation
Datasheet
Receiving Frames with 9 Data
Bits
2543C–AVR–12/03
If 9-bit characters are used (UCSZ=7) the ninth bit must be read from the RXB8 bit in
UCSRB before reading the low bits from the UDR. This rule applies to the FE, DOR and
UPE Status Flags as well. Read status from UCSRA, then data from UDR. Reading the
UDR I/O location will change the state of the receive buffer FIFO and consequently the
TXB8, FE, DOR and UPE bits, which all are stored in the FIFO, will change.
The following code example shows a simple USART receive function that handles both
nine bit characters and the status bits.
Note:
Assembly Code Example
C Code Example
USART_Receive:
USART_ReceiveNoError:
unsigned int USART_Receive( void )
{
}
; Wait for data to be received
sbis UCSRA, RXC
rjmp USART_Receive
; Get status and 9th bit, then data from buffer
in
in
in
; If error, return -1
andi r18,(1<<FE)|(1<<DOR)|(1<<UPE)
breq USART_ReceiveNoError
ldi
ldi
; Filter the 9th bit, then return
lsr
andi r17, 0x01
ret
unsigned char status, resh, resl;
/* Wait for data to be received */
while ( !(UCSRA & (1<<RXC)) )
/* Get status and 9th bit, then data */
/* from buffer */
status = UCSRA;
resh = UCSRB;
resl = UDR;
/* If error, return -1 */
if ( status & (1<<FE)|(1<<DOR)|(1<<UPE) )
/* Filter the 9th bit, then return */
resh = (resh >> 1) & 0x01;
return ((resh << 8) | resl);
1. The example code assumes that the part specific header file is included.
return -1;
For I/O Registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”,
and “SBI” instructions must be replaced with instructions that allow access to
r18, UCSRA
r17, UCSRB
r16, UDR
r17, HIGH(-1)
r16, LOW(-1)
r17
;
(1)
(1)
ATtiny2313/V
123

Related parts for ATTIny2313-16MI