Adventures with a Single Board Computer

CPU NatSemi Geode operating at frequencies of 200/233/266/300 MHz (with a default speed of 233 MHz on-board) or refer to the Geode link. The VGA/LCD interface is NS GX5530, featuring shared memory of 2.5MB, supporting CRT displays and 18-bit TFT LCDs with a resolution of up to 1024x768 at 64K colors, equipped with VGA and 50-pin LCD connectors. The single-board computer (SBC) is powered via a standard power connector supplying +5V, 0V, 0V, and +12V. The current consumption at -5V and -12V is uncertain; however, it is believed that the board does not require -5V and utilizes an on-board -12V DC-DC inverter for the RS232 port. The total power consumption of the SBC, SB16 sound card, hard disk, and USB hub is approximately 20 watts, with a reduction of about 2 watts when the disk is spun down. There is also an approximate 2-watt variation in CPU power consumption between full load and idle states. It is advisable to avoid using the "no-hlt" kernel option, which sets the disk to spin down on /dev/hda after 15 minutes of inactivity. The -S value is set in multiples of 5 seconds for values 1-240, and in multiples of 30 minutes for values 241-251; refer to the man page for additional values. Many background services frequently access the hard disk, preventing it from spinning down or causing it to spin up too often. Running only essential services is recommended. The following are some of the services that have been optimized: SHELL=/bin/sh PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin. Scheduled tasks include running daily, weekly, and monthly scripts via cron. Additional settings include a cleaning interval, heartbeat interval, and statistics interval. The DNS configuration includes a forwarders list and a logging configuration that reduces verbosity for certain categories. A basic electronic circuit is required to create a mains switch controlled by the Data Terminal Ready (DTR) line of the modem's communication port. When the communication port is activated, the DTR line transitions from -12V to +12V, triggering the mains switch to power the modem. This circuit requires a brief period to change states, necessitating an initialization sequence to ensure the modem is operational before the pppd and chat script execution. As of the stock Linux kernel version 2.2.18, the SBC and SB16 sound card exhibit periodic glitches, resulting in noisy recordings, with further investigation needed to identify the issue or implement low-latency patches.

The CPU NatSemi Geode operates at various frequencies, with the default being set at 233 MHz. This single-board computer (SBC) integrates the NS GX5530 VGA/LCD interface, which utilizes shared memory of 2.5MB and supports both CRT displays and 18-bit TFT LCDs. The maximum resolution achievable is 1024x768 pixels at 64K colors, facilitated by VGA and 50-pin LCD connectors. The power supply requirements for this board include +5V, 0V, 0V, and +12V, ensuring stable operation.

The power consumption characteristics are noteworthy; the SBC, along with the SB16 sound card and hard disk, consumes approximately 20 watts. This consumption can be reduced by about 2 watts when the hard disk is set to spin down after a defined period of inactivity, specifically 15 minutes. The management of power states is crucial to optimizing energy efficiency, particularly by avoiding the "no-hlt" kernel option, which can hinder the system's ability to manage power effectively.

The electronic design also incorporates a mains switch activated by the DTR line of the modem's communication port. This design allows for automated control of the modem's power state, ensuring that it is fully operational before initiating any communication processes. The transition of the DTR line from -12V to +12V serves as the trigger for this mains switch, highlighting the importance of timing in the operation of the modem.

In addition to the power management features, attention is needed regarding the periodic glitches experienced with the audio output from the SB16 sound card. These glitches can affect recording quality, necessitating further investigation into potential solutions, such as low-latency patches, to enhance performance. Overall, the integration of these components within the SBC framework presents a versatile platform for various applications, combining efficient power management with robust multimedia capabilities.CPU NatSemi Geode 200/233/266/300 MHz (default 233 on-board) or and follow Geode link. VGA/LCD Interface NS GX5530, shared memory 2. 5MB, support CRT display and 18-bit TFT LCD, resolution up to 1024x768 @64K colors, with VGA and 50-pin LCD connectors Given that the SBC is powered from a standard +5v, 0v, 0v, +12v power connector, I`m not sure how they measured the current consumption at -5v and -12v :-). I believe the board has no need of -5v and uses an on board -12v DC-DC inverter for the RS232 port. Power used by SBC, SB16, HardDisk and HUB is aprox 20 watts, saving aprox 2 watts when disk spins down. There is a further aprox 2 watts difference in CPU power consumption between it working flat out and being "idle".

It is worth not using the "no-hlt" kernel option. sets disk to spindown on /dev/hda after 180*5 secs = 15 mins of inactivity. The -S value is multiples of 5 secs for 1-240, and multiples of 30mins for 241-251, see man page for other values. Many services continually write to or access the hard disk and prevent spindown from kicking in, or mean it spins up too frequently.

Run just the services you need is always a good plan. Here are some services that I tamed. SHELL=/bin/sh PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin # m h dom mon dow user command 25 21 * * * root run-parts -report /etc/cron. daily 30 21 * * 7 root run-parts -report /etc/cron. weekly 35 21 1 * * root run-parts -report /etc/cron. monthly cleaning-interval 0; heartbeat-interval 0; statistics-interval 0; dialup yes; notify no; forward only; forwarders { 129.

11. 144. 1; }; listen-on port 53 { 127. 0. 0. 1; 192. 168. 10. 80; }; // reduce log verbosity on issues outside our control logging { category lame-servers { null; }; category statistics { null; }; category cname { null; }; }; A bit of electronics needed to make a mains switch controlled by the DTR line of the modem comms port. When the comms port is made active, the DTR line goes from -12v to +12v, triggering the mains switch to power up the modem.

The circuit takes a little while to change state. Because the modem doesn`t come on immediately, some form of "initialise" is needed to make sure the modem is powered up and ready by the time pppd and the chat script is running. As of stock Linux kernel 2. 2. 18, this SBC and the SB16 sound card give periodic glitches, making recording a bit noisy. I`ve not bottomed the problem or tried the low latency patches. 🔗 External reference