AT89C51RB2 Atmel Corporation, AT89C51RB2 Datasheet - Page 56

• Manufacturer Part Number: AT89C51RB2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RB2

• Flash (kbytes): 16 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 32
• Spi: 1
• Uart: 1
• Sram (kbytes): 1.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART
• Watchdog: Yes

Registers
56
AT89C51RB2/RC2
A low-priority interrupt can be interrupted by a high-priority interrupt, but not by another
low-priority interrupt. A high-priority interrupt can’t be interrupted by any other interrupt
source.
Table 43. Priority Level Bit Values
If two interrupt requests of different priority levels are received simultaneously, the
request of higher-priority level is serviced. If interrupt requests of the same priority level
are received simultaneously, an internal polling sequence determines which request is
serviced. Thus within each priority level there is a second priority structure determined
by the polling sequence.
IPH. x
0
0
1
1
IPL. x
0
1
0
1
Interrupt Level Priority
3 (Highest)
0 (Lowest)
1
2
4180E–8051–10/06