WB 4: Errata

0430001: the error in the measurement of resistances

Revision:

4.3

'Description

The R1 and R2 channels on the Wiren Board 4 are for resistance measurement. Technical details are described in the article ADC:resistance measurement - technical details. To measure resistance, you need to know the value of two constants: r1 and r2. The R1 constant has a spread of up to 10% from device to device.

How to fix

You must calibrate the channels to obtain the r1 and r2 values for your device. The R2 value has a small spread, so in practice you can limit the value to r1. The value of r1, obtained when testing in production, can be obtained by request support@wirenboard.com (specify S/N of the device).

The exact value of r1 must be specified in the /etc/wb-homa-adc file.conf .

0430002: features of watchdog

Revision:

4.3

'Description

Watchdog (watchdog) works independently of the power button. When you turn on the device with the button, it is possible that the watchdog is in part of the cycle with the power off of the Board. In this case, the Board will be turned off, the power led will not light until the end of the watchdog cycle (up to 10 seconds).

Symptoms

1) the power Led will light up only after some time (up to 10 seconds) after the device is turned on by the button. 2) the power Led stops burning a few seconds after the device is turned on and lights up again a few seconds later.

How to fix This behavior does not affect the health of the device.