First Steps with the BeagleBoard
The BeagleBoard, capabale as it is, is not a standard PC, and thus beginning to work with is involves some non trivial steps.
The first step, naturally, is to get keyboard, mouse and monitor output. The second step is to get network controll (preferably Ethernet, but a Serial connection is fine for the beginning as well).
Connecting Keyboard, Mouse and Monitor to the BeagleBoard
The BeagleBoard comes with the following connections:
- Video Connectors
- DVI-D via a HDMI connector #3)
- S-Video (15)
- Control Inputs:
- RS-232 Serial Header (10)
- USB 2.0 HS OTG (12)
Keyboard and Mouse connection
What is USB OTG?
USB On-The-Go, normally abbreviated USB OTG, is a supplement to the USB 2.0 specification.
The standard USB uses a master/slave architecture; a USB ‘Host’ acts as the protocol master, and a USB ‘Device’ acts as the slave. Only the Host can schedule the configuration and data transfers over the link. The Devices cannot initiate data transfers, they only respond to requests given by a host.
OTG introduces the concept that a ‘Device’ can perform both the master and slave roles, and so subtly changes the terminology. Now a ‘Device’ can be either a ‘Host’ (acting as the link master) or a ‘Peripheral’ (acting as the link slave).
The Device connected to the ‘A’ end of the cable at startup acts as the Default Host, while the ‘B’ end acts as the Default Peripheral.
The USB OTG port is the default power input of the BeagleBoard. In order to use is as a USB host, and connect a USB hub to it, you must power the BeagleBoard using the +5v power supply connector (11). Also, a USB hub with an external power supply should be used, as the BeagleBoard can source only 100mA.
In order to “configure” the OTG port to run in Host mode (rather than device), there are three options:
- Short connect pin4 (ID) and pin5 (GND) on the BeagleBoard
- Use a standard miniB cable and connect the pins
- Get a USB OTG (5-wire) cable.
Serial Connection to the BeagleBoard
The serial header on the BeagleBoard is an IDC-10 connector. In order to connect it to the serial port in the PC, a “null modem” cable should be used. Here’s the pin connection diagram for a serial null modem:
| Signal Name | DB-25 Pin | DE-9 Pin | DE-9 Pin | DB-25 Pin | ||
| FG (Frame Ground) | 1 | - | X | - | 1 | FG |
| TD (Transmit Data) | 2 | 3 | - | 2 | 3 | RD |
| RD (Receive Data) | 3 | 2 | - | 3 | 2 | TD |
| RTS (Request To Send) | 4 | 7 | - | 8 | 5 | CTS |
| CTS (Clear To Send) | 5 | 8 | - | 7 | 4 | RTS |
| SG (Signal Ground) | 7 | 5 | - | 5 | 7 | SG |
| DSR (Data Set Ready) | 6 | 6 | - | 4 | 20 | DTR |
| CD (Carrier Detect) | 8 | 1 | - | 4 | 20 | DTR |
| DTR (Data Terminal Ready) | 20 | 4 | - | 1 | 8 | CD |
| DTR (Data Terminal Ready) | 20 | 4 | - | 6 | 6 | DSR |
Configuring Serial Connection
There are two nice serial connection programs in my distribution (Debian): minicom and cutecom. minicom is non-graphical, and cutecom is. I have used minicom years ago to connect to the Internet using a modem, so I liked the chance to use it again.
Minicom should be configured with the following settings (except the serial device which should be changed to the device that was used).
+-------------------------------------------------------+
| A - Serial Device : /dev/ttyS2 |
| B - Lockfile Location : /var/lock |
| C - Callin Program : |
| D - Callout Program : |
| E - Bps/Par/Bits : 115200 8N1 |
| F - Hardware Flow Control : No |
| G - Software Flow Control : No |
| |
| Change which setting? |
+-------------------------------------------------------+After saving the settings, restaring minicom and reseting the BeagleBoard, the serial connection is working! Hooray!
I now have a basic network control (with keyboard input) over the BeagleBoard. The next step is to install an Embedded Linux Distribution and proceed from there.
