SAB80C517-M16 SIEMENS [Siemens Semiconductor Group], SAB80C517-M16 Datasheet - Page 262

• Manufacturer Part Number: SAB80C517-M16
• Description: 8-Bit CMOS Single-Chip Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Conclusion
This application example is meant to show that the CCU of the SAB 80C517 is able to generate
very fast PWM signals with low CPU effort.
Small single-chip systems which have to manage PWM periods below 50 microseconds require a
very efficient on-chip timer hardware to leave enough CPU time to perform other control tasks in
real time.
The SAB 80C517 takes advantage of the fast compare timer and the TOC loading mechanism to
meet the above requirements.
10.2
Figure 10-4 shows an example of how to connect an external program and data memory to the SAB
80C517/80C537. For the program memory a standard EPROM 2764A is used. An 8-Kbyte static
RAM 5565 serves as external data memory. The 74HCT573 works as address latch. The address
space ranges from 0 to 1FFF H (8 Kbyte). Pin EA is tied low, so all program memory accesses are
done from external memory. Port 0 is the multiplexed address/data bus, while port 2 always emits
the high order byte of the address. Therefore, in this configuration port 0 and port 2 must not be
used as general-purpose l/O ports.
Semiconductor Group
Using an SAB 80C537 with External Program Memory and Additional External Data
Memory
263
Application Examples