1. General Information

️· Microcontroller: eorex EU1020
️· Document Version: Dec. 09, www.eorex.com
️· Address Space: It utilizes addresses from `03H` to `2FFFH` for various registers and control.

2. Interrupt Sources & Priority (from Interrupt Vector Table - addresses 2FFEH to 2FFFH and beyond)

The EU1020 has multiple interrupt sources, ranked by priority (lower address = higher priority, meaning it gets serviced first):

️· Reset: Highest priority (address 2FFCH/2FFDH)
️· Real-Time Counter (RTC): Priority 2 (address 2FFCH/2FFDH). Configurable clock source and frequency (UCCLK, RTC1, RTC0 bits). Can be driven by Fosc and configurable frequency options such as TT/32, TT/64, TT/128, TT/256. Needs to be enabled with RTCINT and RTCEN.
️· Base Timer: Priority 3 (Address 03H, UCCLK, BASE0, BASE1)
️· Watchdog Timer: (Mentioned but no specific address given).
️· Other Interrupts: (Addresses 2FFEH to 2FFFH and beyond) - includes the rest of the interrupt vector table, with various interrupt sources. The provided text lists these by priority, but without specific functional descriptions beyond "Reserved".

3. Real-Time Counter Details (Register 03H)

️· Address: 03H
️· Name: UCCLK, BASE1, BASE0, RTC1, RTC0, RCSEL2, RCSEL1, RCEl0
️· Function: Configures the real-time counter's operation, including:
- UCCLK: Related to the clock source and frequency options
- RTC1, RTC0: Selects the real-time counter frequency divider (TT/32, TT/64, TT/128, TT/256)
- BASE1, BASE0: Presumed to be related to a base timer configuration.
- RCSEL2, RCSEL1, RCSEL0: (presumed to be related to real-time counter selection)
️· Default Values: All bits are 0 by default.

4. Important Notes/Observations

️· Repetitive Information: The text has a *significant* amount of repetition. The description of the Real-Time Counter is repeated multiple times, almost verbatim.
️· Limited Function Descriptions: While the addresses and bit names are provided, the descriptions of many registers and interrupt sources are very brief and lack detailed explanation.
️· Clock Source Options: The ability to choose a clock source (potentially ExCLK/PB3) and divider values allows for flexible configuration of interrupt frequencies.
️· Unclear functionality: BASE1, BASE0, RCSEL2, RCSEL1, RCEl0 have not been explained in detail.