🛰️ Mission Command List Guide
This guide explains how to structure and use UART commands sent to the COM PIC, which forwards them to the Main PIC. These commands are used for simulation and control during testing. While the actual command is 14 bytes, the simulator expects 25 bytes.
📦 Command Packet Format
Each Mission Command consists of the following:
| Byte Index | Field | Description |
|---|---|---|
| 0 | Header | Always 0x42 |
| 1 | Satellite ID | Always 0x57 |
| 2 | Reservation Time | Set to 0x00 |
| 3 | Command ID0 | Set to 0xB4 |
| 4 | Command ID1 | Varies – defines the operation (see below) |
| 5–11 | Mission Mode / Data | Payload (mode settings, packet numbers, etc.) |
| 12–13 | CRC | CRC0 (LSB), CRC1 (MSB) – Checksum of first 12 bytes |
| 14–24 | Padding (0x00) | Simulator requires 25-byte total length |
Note: During actual command transmission, only the first 14 bytes are used.
🔧 Commands and Usage
| # | Command ID1 | Description | Mission Data | Example Command |
|---|---|---|---|---|
| 1 | 0x00 | TURN OFF DP | All 0x00 | 42 57 00 B4 00 00 00 00 00 00 00 00 CRC0 CRC1 |
| 2 | 0x00 | ACTIVATE DP (Default Mode) | All 0x00 | 42 57 00 B4 00 00 00 00 00 00 00 00 CRC0 CRC1 |
| 3 | 0x01 | ACTIVATE SF Mode | All 0x00 | 42 57 00 B4 01 00 00 00 00 00 00 00 CRC0 CRC1 |
| 4 | 0x01 | Transfer 1 data packet | All 0x00 | 42 57 00 B4 01 00 00 00 00 00 00 00 CRC0 CRC1 |
| 5 | 0x00 | Transfer all packets | All 0x00 | 42 57 00 B4 00 00 00 00 00 00 00 00 CRC0 CRC1 |
| 6 | 0x00 | Transfer N packets (custom) | Byte 4 = N | 42 57 00 B4 NN 00 00 00 00 00 00 00 CRC0 CRC1 |
🧮 CRC Calculation
Use CRC-16-CCITT (or your protocol-specific CRC) on the first 12 bytes ([0] to [11]) to generate:
- CRC0 (LSB)
- CRC1 (MSB)
💻 Sending Over UART
- Construct a 14-byte array:
[0] to [13] - Pad with 11 zeroes if needed for simulation:
[14] to [24] - Transmit the 25-byte buffer over UART to COM PIC
- COM PIC routes to MAIN PIC for action
📘 Summary
- Actual command = 14 bytes (Header + Payload + CRC)
- Simulated command = 25 bytes (padded with zeroes)
- All commands go through COM PIC to MAIN PIC
- Command ID1 and payload define the operation
- CRC must be valid to accept command