AT90PWM3B Atmel Corporation, AT90PWM3B Datasheet - Page 189

• Manufacturer Part Number: AT90PWM3B
• Manufacturer: Atmel Corporation

Specifications of AT90PWM3B

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 8
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 27
• Ext Interrupts: 4
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 125
• Analog Comparators: 3
• Resistive Touch Screen: No
• Dac Channels: 1
• Dac Resolution (bits): 10
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 105
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 5
• Output Compare Channels: 16
• Input Capture Channels: 1
• Pwm Channels: 12
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

18.6
4317J–AVR–08/10
Data Transmission – USART Transmitter
that there are no unread data in the receive buffer. Note that the TXC flag must be cleared
before each transmission (before UDR is written) if it is used for this purpose.
The following simple USART initialization code examples show one assembly and one C func-
tion that are equal in functionality. The examples assume asynchronous operation using polling
(no interrupts enabled) and a fixed frame format. The baud rate is given as a function parameter.
For the assembly code, the baud rate parameter is assumed to be stored in the r17:r16
Registers.
Note:
More advanced initialization routines can be made that include frame format as parameters, dis-
able interrupts and so on. However, many applications use a fixed setting of the baud and
control registers, and for these types of applications the initialization code can be placed directly
in the main routine, or be combined with initialization code for other I/O modules.
The USART Transmitter is enabled by setting the Transmit Enable (TXEN) bit in the UCSRB
Register. When the Transmitter is enabled, the normal port operation of the TxDn pin is overrid-
den by the USART and given the function as the Transmitter’s serial output. The baud rate,
mode of operation and frame format must be set up once before doing any transmissions. If syn-
Assembly Code Example
C Code Example
TABLE 2.
USART_Init:
void USART_Init( unsigned int baud )
{
}
; Set baud rate
sts
sts
; Set frame format: 8data, no parity & 2 stop bits
ldi
sts
; Enable receiver and transmitter
ldi
sts
ret
/* Set baud rate */
UBRRH = (unsigned char)(baud>>8);
UBRRL = (unsigned char)baud;
/* Set frame format: 8data, no parity & 2 stop bits */
UCSRC = (0<<UMSEL)|(0<<UPM0)|(1<<USBS)|(3<<UCSZ0);
/* Enable receiver and transmitter */
UCSRB = (1<<RXEN0)|(1<<TXEN0);
1. The example code assumes that the part specific header file is included.
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 extended I/O. Typically
“LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and “CBR”.
UBRRH, r17
UBRRL, r16
r16, (0<<UMSEL)|(0<<UPM0)|(1<<USBS)|(3<<UCSZ0)
UCSRC,r16
r16, (1<<RXEN0)|(1<<TXEN0)
UCSRB,r16
(1)
(1)
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