System Configuration for the ‘b

A new feature of 1.1 is the ability to store system configurations on the SD card. This will allow us to remove any system-specific settings from code and b programs as well as allow us to configure some things that have not been easy until now.

The config file is located in /config/sys.b and looks like this:

If you have a version of the ‘b that shipped before the 1.1 firmware, then you will need to manually create the folder and create the file yourself.

Gain Mode

Allows you to specify whether or not your model supports +/- 5V operation or +/- 10V operation. HIGH indicates 10V and LOW indicates 5V.

Possible Values:
HIGH
LOW

LED Dim

Allows you to specify a dimness for the blue output LEDs. Higher numbers are dimmer, and lower are brighter. The factory default value is 50. A value of 10 results in no dimming at all (and is very bright). A value of 100 results in 1/10th the brightness and 1000 results in 1/100th brightness.

Output Tune

Having 16 channels of output, each with it’s own gain adjustment and only a single offset pot, makes it nearly impossible to get a ‘b in perfect tune. And if you’re a like me, you’ll spend way too much time tweaking those pots to as close to perfection as possible.

With a software-based tuning algorithm you only need to get them as close as reasonably possible (within 10-50mV) and the rest can be finished in configuration. For a +/­ 10V model (which are particularly difficult to tune due to the gain staging), it is possible to get each of the 16 channels to have a +/- 1mV zero point and to have an average 40mV improvement at the far end of the scale, translating to tracking within about 0.1%.

To calculate the values you need to plug in, you can download a spreadsheet that will walk you through the required steps. All you will need is a reasonably accurate digital voltmeter.

nw2s-b-software-tuning-spreadsheet (XLSX, 51.2 kB)

Input Tune

Similarly to the output tuning, having a fixed bias network and only a single offset pot, some of the inputs need a little tuning to increase the precision. Use the same download as above and check out the second worksheet.

Other model information

As you can see, there are some further settings that will provide for future differentiation in subsequent models. Yes, there’s some work on that front, so be patient.

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