2. MSC Getting Started

Interfacing | Default / Fast Configuration | Send Data | Get Data | Performance

MiniSatCom can be operated within minutes of a user first opening the package. The MiniSatCom Developers Board helps speed the time-to-operation by providing all the necessary electrical and RF connections for successful packet transmission. Always follow ESD Protections.

2.1. Interfacing for Testing

MiniSatCom should be bolted onto the Developers Board, as shown here. The antenna should be installed, as shown here. The MiniSatCom Developers Board can be interfaced directly into a computer or other USB host. The board can be powered over dedicated power USB (red arrow), and communicate with a separate serial port through an FTDI module (blue arrow) on the Developers Board. All necessary wires are included with the Developers Board. The operator can immediately operate the radio over a serial port with the commands below.

Initial switch positions

    1. “RF Enable” to “On”
    2. “Power Selection” to “USB Power”
    3. “VCC IO Selection” to “Power Source”
    4. “Serial Port Selection” to “FTDI”
    5. All “External Header Pin Enable Switches” to “Open”

The default setup of MiniSatCom UHF is designed for basic small satellite packet radio operations, compatible with most amateur radio ground stations operations at 9600 baud.

2.2. Default Configuration

Modulation:  GFSK
RF Data Rate:  9600 bits/second
RF Transmission Power:  30 dBm (1 Watt)
RF Receive Sensitivity:  -110dBm
Data Interface:  Asynchronous Serial TTL - 115200 bits/second (8 data bits –  1 start bit – no parity)
Serial Flow control:  Hardware: CTS/DSR/DTR
Disabled remote command or encryption
No encryption of data field
Deviation of 0,1 bits is +/- 3kHz from center frequency

2.3. Fast Configuration

A first time user will need to perform the following steps over the serial port through the onboard USB FTDI module. These settings are non-volatile, meaning they will be retained after losing power for any duration.

    1. Enable each port intended to be used. See below for “2.3.1. Port Control”
    2. Configure each port’s frequency. See below for “2.3.2. Frequency control”
    3. Load the default AX.25 configuration. See below for “2.3.3. AX.25 defaults”

A full list of functions are available in “3.3. Digital Interface

2.3.1. Port Control

Detailed description:

To set a port as enabled or disabled, use a settings command for a given port enable setting. Elements are separated by commas.

Example: Enable transmit port 0

CHAR: s,0,p,e,ecr HEX: 0x73 2C 30 2C 70 2C 65 2C 65 2C 0D

2.3.2. Frequency control

To configure a port’s frequency, use a settings command for a given port modulation setting. Select the port number and frequency as needed, Ports: ‘0’ to ‘3’ and ‘R’. Send the flowing command:

Example: Set transmit port 0 to 435 MHz

CHAR: s,0,m,f,435000000cr HEX: 0x73 2C 30 2C 6D 2C 66 34 33 35 30 30 30 30 30 30 2C 0D

Example: Set receive port to 435 MHz

CHAR: s,R,m,f,435000000cr HEX: 0x73 2C 52 2C 6D 2C 66 34 33 35 30 30 30 30 30 30 2C 0D

2.3.3. AX.25 defaults

The AX.25 default configuration specifies the beginning fields of the KISS TNC packet. Within this, the transmit port and all addresses/callsigns are declared. The default control (0x03) and protocol (0xf0) will be used. Detailed use is described in section 2.3, “AX.25 defaults”.

This array should be frame escaped between the flags.

Example: Set transmit port 0 to AX.25 with SSID 1, destination callsign APRB00, source callsign NOCALL

HEX: 0x73 2C 61 2C 00 82 A0 A4 84 60 60 E2 9C 9E 882 98 98 63 0D

Reply in HEX: 0x41 58 2E 32 35 20 68 65 61 64 65 72 3A 20 00 82 A0 A4 84 60 60 E2 9C 9E 86 82 98 98 63 03 F0 0D 0A

2.4. Fast Send Data

2.4.1. Message Packet

Once the settings above are established, sending a message is simple. To send a basic ascii message, start the frame with a colon or dollar sign and end with a carriage return. This will become the data field of the default AX.25 frame, as configured in 2.2.3.

Example: Send ‘:Hello Worldcr’

CHAR: :Hello Worldcr HEX: 0x3A 48 65 6C 6C 6F 20 57 6F 72 6C 64 0D

Example: Send ‘$Hello Worldcr’

CHAR: $Hello Worldcr HEX: 0x24 48 65 6C 6C 6F 20 57 6F 72 6C 64 0D

This should result in the data being received by other configured MiniSatCom devices.

2.5. Get Data

All received packets are Checksum verified. If the Checksum passes, the packet is encapsulated in a KISS TNC packet and is sent to the user. RF packets received will not be used as a command to configure the radio.

Remote reconfiguration will be enabled in future software versions. A user could, however, remotely command the payload to send the reconfiguration through USART, SPI, or TWI.

2.6. Expected Performance

The default configuration should result in the following performance values

General Performance
RF TX power 25 to 30 dBm
RF RX sensitivity -110 dBm (LNA is powered off)
Transmit power 5V – 0.390A
Receive power 5V – 0.010A
Idle power 5V – <0.003A