 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
AT89LP52-20AU Datasheet(PDF) 11 Page - ATMEL Corporation |
|
||||||||||||||||||||||||||||||
AT89LP52-20AU Datasheet(HTML) 11 Page - ATMEL Corporation |
|
|
11 / 113 page  11 3709B–MICRO–12/10 AT89LP51/52 - Preliminary 3.1.1 External Program Memory Interface The AT89LP51/52 uses the standard 8051 external program memory interface with the upper address on Port 2, the lower address and data in/out multiplexed on Port 0, and the ALE and PSEN strobes. Program memory addresses are always 16-bits wide, even though the actual amount of program memory used may be less than 64K byes. External program execution sacri- fices two full 8-bit ports, P0 and P2, to the function of addressing the program memory. Figure 3-2 shows a hardware configuration for accessing up to 64K bytes of external ROM using a 16-bit linear address. Port 0 serves as a multiplexed address/data bus to the ROM. The Address Latch Enable strobe (ALE) is used to latch the lower address byte into an external reg- ister so that Port 0 can be freed for data input/output. Port 2 provides the upper address byte throughout the operation. PSEN strobes the external memory. Figure 3-3 shows the timing of the external program memory interface. ALE is emitted at a con- stant rate of 1/3 of the system clock with a 1/3 duty cycle. PSEN is emitted at a similar rate, but with 50% duty cycle. The new address changes in the middle of the ALE pulse for latching on the falling edge and is tristated at the falling edge of PSEN. The instruction data is sampled from P0 and latched internally during the high phase of the clock prior to the rising edge of PSEN. This timing applies to both Compatibility and Fast modes. In Compatibility mode there is no dif- ference in instruction timing between internal and external execution. Figure 3-2. Executing from External Program Memory Figure 3-3. External Program Memory Fetches AT89LP EXTERNAL PROGRAM MEMORY INSTR. ADDR OE PSEN P3 P2 ALE P0 P1 LATCH CLK ALE PSEN FLOAT PCL OUT P0 PCH OUT P2 PCH OUT PCH OUT DATA SAMPLED PCL OUT PCL OUT DATA SAMPLED DATA SAMPLED |
Similar Part No. - AT89LP52-20AU |
|
Similar Description - AT89LP52-20AU |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
