ATMEGA128-16AI Atmel, ATMEGA128-16AI Datasheet - Page 34

• Manufacturer Part Number: ATMEGA128-16AI
• Description: IC AVR MCU 128K 16MHZ 64-TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA128-16AI

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 128KB (64K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• For Use With: ATSTK501 - ADAPTER KIT FOR 64PIN AVR MCU
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: Q1167170A

Using all 64 Kbyte
Locations of External
Memory
34
ATmega128
Since the External Memory is mapped after the Internal Memory as shown in
Kbyte of External Memory is available by default (address space 0x0000 to 0x10FF is reserved
for internal memory). However, it is possible to take advantage of the entire External Memory by
masking the higher address bits to zero. This can be done by using the XMMn bits and control
by software the most significant bits of the address. By setting Port C to output 0x00, and releas-
ing the most significant bits for normal Port Pin operation, the Memory Interface will address
0x0000 - 0x1FFF. See the following code examples.
Note:
Care must be exercised using this option as most of the memory is masked away.
Assembly Code Example
C Code Example
#define OFFSET 0x2000
void XRAM_example(void)
{
unsigned char *p = (unsigned char *) (OFFSET + 1);
DDRC = 0xFF;
PORTC = 0x00;
XMCRB = (1<<XMM1) | (1<<XMM0);
*p = 0xaa;
XMCRB = 0x00;
*p = 0x55;
}
; OFFSET is defined to 0x2000 to ensure
; external memory access
; Configure Port C (address high byte) to
; output 0x00 when the pins are released
; for normal Port Pin operation
ldi
out
ldi
out
; release PC7:5
ldi
sts
; write 0xAA to address 0x0001 of external
; memory
ldi
sts
; re-enable PC7:5 for external memory
ldi
sts
; store 0x55 to address (OFFSET + 1) of
; external memory
ldi
sts
1. See “About Code Examples” on page 8.
r16, 0xFF
DDRC, r16
r16, 0x00
PORTC, r16
r16, (1<<XMM1)|(1<<XMM0)
XMCRB, r16
r16, 0xaa
0x0001+OFFSET, r16
r16, (0<<XMM1)|(0<<XMM0)
XMCRB, r16
r16, 0x55
0x0001+OFFSET, r16
(1)
(1)
Figure
2467V–AVR–02/11
11, only 60