ATMEGA48-20PI Atmel, ATMEGA48-20PI Datasheet - Page 220

• Manufacturer Part Number: ATMEGA48-20PI
• Description: IC AVR MCU 4K 5V 20MHZ 28-DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA48-20PI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 4KB (2K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 6x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 28-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: ATMEGA48-24PI; ATMEGA48-24PI

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Assembly Code Example
ATmega48/88/168
ldi
(1<<TWINT)|(1<<TWSTA)|
out
wait1:
in
sbrs r16,TWINT
rjmp wait1
in
andi r16, 0xF8
cpi
brne ERROR
ldi
out
ldi
(1<<TWEN)
out
wait2:
in
sbrs r16,TWINT
rjmp wait2
in
andi r16, 0xF8
cpi
brne ERROR
ldi
out
ldi
(1<<TWEN)
out
wait3:
in
sbrs r16,TWINT
rjmp wait3
in
andi r16, 0xF8
cpi
brne ERROR
ldi
(1<<TWINT)|(1<<TWEN)|
out
r16,
(1<<TWEN)
TWCR, r16
r16,TWCR
r16,TWSR
r16, START
r16, SLA_W
TWDR, r16
r16, (1<<TWINT) |
TWCR, r16
r16,TWCR
r16,TWSR
r16, MT_SLA_ACK
r16, DATA
TWDR, r16
r16, (1<<TWINT) |
TWCR, r16
r16,TWCR
r16,TWSR
r16, MT_DATA_ACK
r16,
(1<<TWSTO)
TWCR, r16
C Example
TWCR = (1<<TWINT)|(1<<TWSTA)|
while (!(TWCR & (1<<TWINT)))
if ((TWSR & 0xF8) != START)
TWDR = SLA_W;
TWCR = (1<<TWINT) |
(1<<TWEN);
while (!(TWCR & (1<<TWINT)))
if ((TWSR & 0xF8) !=
MT_SLA_ACK)
TWDR = DATA;
TWCR = (1<<TWINT) |
(1<<TWEN);
while (!(TWCR & (1<<TWINT)))
if ((TWSR & 0xF8) !=
MT_DATA_ACK)
TWCR = (1<<TWINT)|(1<<TWEN)|
(1<<TWEN)
(1<<TWSTO);
;
ERROR();
;
ERROR();
;
ERROR();
Comments
Send START condition
Wait for TWINT Flag set. This
indicates that the START
condition has been transmitted
Check value of TWI Status
Register. Mask prescaler bits. If
status different from START go to
ERROR
Load SLA_W into TWDR
Register. Clear TWINT bit in
TWCR to start transmission of
address
Wait for TWINT Flag set. This
indicates that the SLA+W has
been transmitted, and
ACK/NACK has been received.
Check value of TWI Status
Register. Mask prescaler bits. If
status different from
MT_SLA_ACK go to ERROR
Load DATA into TWDR Register.
Clear TWINT bit in TWCR to
start transmission of data
Wait for TWINT Flag set. This
indicates that the DATA has been
transmitted, and ACK/NACK has
been received.
Check value of TWI Status
Register. Mask prescaler bits. If
status different from
MT_DATA_ACK go to ERROR
Transmit STOP condition
2545S–AVR–07/10