ATMEGA32U4-MU Atmel, ATMEGA32U4-MU Datasheet - Page 218

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ATMEGA32U4-MU

Manufacturer Part Number
ATMEGA32U4-MU
Description
MCU AVR 32K FLASH 16MHZ 44-QFN
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA32U4-MU

Core Processor
AVR
Core Size
8-Bit
Speed
16MHz
Connectivity
I²C, SPI, UART/USART, USB
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
26
Program Memory Size
32KB (16K x 16)
Program Memory Type
FLASH
Eeprom Size
1K x 8
Ram Size
2.5K x 8
Voltage - Supply (vcc/vdd)
2.7 V ~ 5.5 V
Data Converters
A/D 12x10b
Oscillator Type
External
Operating Temperature
-40°C ~ 85°C
Package / Case
44-VQFN
Package
44QFN EP
Device Core
AVR
Family Name
ATmega
Maximum Speed
16 MHz
Operating Supply Voltage
3.3|5 V
Data Bus Width
8 Bit
Number Of Programmable I/os
26
Interface Type
EBI/I2S/SPI/TWI/USART/USB
On-chip Adc
12-chx10-bit
Number Of Timers
5
For Use With
ATSTK524 - KIT STARTER ATMEGA32M1/MEGA32C1ATSTK600 - DEV KIT FOR AVR/AVR32ATAVRDRAGON - KIT DRAGON 32KB FLASH MEM AVRATSTK500 - PROGRAMMER AVR STARTER KIT
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
ATMEGA32U4-16MU
ATMEGA32U4-16MU

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATMEGA32U4-MUR
Manufacturer:
UCC
Quantity:
1 001
7766F–AVR–11/10
After initialization the USART is ready for doing data transfers. A data transfer is initiated by writ-
ing to the UDRn I/O location. This is the case for both sending and receiving data since the
transmitter controls the transfer clock. The data written to UDRn is moved from the transmit buf-
fer to the shift register when the shift register is ready to send a new frame.
Note:
The following code examples show a simple USART in MSPIM mode transfer function based on
polling of the Data Register Empty (UDREn) Flag and the Receive Complete (RXCn) Flag. The
USART has to be initialized before the function can be used. For the assembly code, the data to
be sent is assumed to be stored in Register R16 and the data received will be available in the
same register (R16) after the function returns.
The function simply waits for the transmit buffer to be empty by checking the UDREn Flag,
before loading it with new data to be transmitted. The function then waits for data to be present
in the receive buffer by checking the RXCn Flag, before reading the buffer and returning the
value.
Assembly Code Example
C Code Example
USART_MSPIM_Transfer:
USART_MSPIM_Wait_RXCn:
unsigned char USART_Receive( void )
{
}
; Wait for empty transmit buffer
sbis UCSRnA, UDREn
rjmp USART_MSPIM_Transfer
; Put data (r16) into buffer, sends the data
out UDRn,r16
; Wait for data to be received
sbis UCSRnA, RXCn
rjmp USART_MSPIM_Wait_RXCn
; Get and return received data from buffer
in r16, UDRn
ret
/* Wait for empty transmit buffer */
while ( !( UCSRnA & (1<<UDREn)) );
/* Put data into buffer, sends the data */
UDRn = data;
/* Wait for data to be received */
while ( !(UCSRnA & (1<<RXCn)) );
/* Get and return received data from buffer */
return UDRn;
To keep the input buffer in sync with the number of data bytes transmitted, the UDRn register must
be read once for each byte transmitted. The input buffer operation is identical to normal USART
mode, i.e. if an overflow occurs the character last received will be lost, not the first data in the buf-
fer. This means that if four bytes are transferred, byte 1 first, then byte 2, 3, and 4, and the UDRn
is not read before all transfers are completed, then byte 3 to be received will be lost, and not byte
1.
(1)
(1)
ATmega16/32U4
218

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