Position encoding in battery-powered electronics: Page 3 of 5

October 09, 2014 //By Jonas Kupp and David Lin
Position encoding in battery-powered electronics
Jonas Kupp and David Lin consider the benefits of position encoding in battery-powered electronics.
to wake up the microcontroller is available. If multiple position values are required, like e.g. in a mobile multi-axis robot, cascading multiple iC-TW11s via an SPI chain and interrupt lines is possible by design. Since the maximum accuracy is not always required, the integrated filter function can be switched off to save even more energy.

In normal operation, iC-TW11 reaches sampling rates of 4 kHz with activated filter and automatic amplifier calibration for maximum accuracy with 10-bit resolution. If the filter is deactivated, the latency period is reduced to 50 µs and sampling rates of up to 20 kHz are possible. With the same sampling rate, the current consumption is typically reduced by almost 90 % due to the filter deactivation. A measuring cycle can be started by the microcontroller or via a separate trigger input, i.e. through an external event. If a new position value is available, the microcontroller is switched from standby mode to active operation via an interrupt. The absolute position data is read via the 4-wire SPI interface with clock rates up to 16 MHz. A high clock rate also affects a reduction in current consumption because the active times of the iC-TW11 and the microcontroller are reduced. Optionally, the internal raw Hall sensor values (10 bits), the sine and cosine values (12 bits), and the amplification factor (18 steps) can be requested for test purposes or for the measurement of the magnetic airgap.

An energy harvesting solution, e.g. with wireless sensors, can be used instead of a battery if the peak currents are supplied from a capacitor. For digital control buttons, ultra-cap buffering to ride through power failures is possible.

Switching Supply Lines

In some applications, an energy-efficient position measurement is required even when external power is not available. For robots, which due to their inertia can move even after power failure, it is dangerous if the change in position is not recognized and the

Design category: 

Vous êtes certain ?

Si vous désactivez les cookies, vous ne pouvez plus naviguer sur le site.

Vous allez être rediriger vers Google.