One of the most frustrating issues is when threads activate partially. Symptoms include:
Diagnosis: Use the maintenance terminal (if available) via RS-232 (9600 baud, 8N1). Send the command $ACT.STATUS. Expected response on a healthy system: THREADS: 3/3 COMPLETE. Any lower number indicates the thread requirement not satisfied. petka 85 86 88 activation thread requirement
Upon power-up (or after a hardware reset), the Petka CPU executes a small bootstrap loader stored in an EPROM. This loader immediately calls the ACTIVATE interrupt (INT 0x42 on Petka 86/88). The INT handler: One of the most frustrating issues is when
After years of field service on Petka systems, these best practices will save you hours of debugging: Diagnosis : Use the maintenance terminal (if available)
| Thread ID | Pin Assignment | Activation Signal | Required Response Time |
|-----------|----------------|-------------------|------------------------|
| Thread 0 | Pin 4 | 1 kHz square wave (5 cycles) | 50ms |
| Thread 1 | Pin 6 | 5V → 0V → 5V ramp (slope ≤ 1V/ms) | 75ms |
| Thread 2 | Pin 8 | Serial data 0xF0 at 19200 baud | 100ms |