ASC - Analog Signal Conditioner

Description

This block converts a fixed-point, discrete signal from analog-to-digital conversion into a normalized command. The block has several parameters that can be set to form the output curve. The ASC is suited for setting the analog sensor (e.g. throttle, brake lever). Transfer characteristic is shown in the picture below, with several different configurations of parameters min, center, max, and direction.

Settings

Parameter min should be set to the value of voltage which is on output on a sensor when is it fully released. Parameter max should be set to the value of voltage which is on output on a sensor when is it fully open. Ideally, the output of the ASC block should be a value from 0-1 (-1 to 1) according to a fully closed and opened analog sensor. In case absmin or absmax are not set, there is no constrain on ASC block output.

The center parameter is a special feature if is set to a non-zero value, the output of the ASC block is bi-directional (suitable for joystick control, or throttle release braking).

In case, when the sensor has the opposite direction of the output (low voltage – max output level), set parameter min to high voltage and parameter max to min voltage, the example is the green line below.

Transfer characteristic of the ASC block

Safety settings

Absmin and absmax are parameters for the detection of malfunction on the input device. If the input value is under absmin or above absmax, output goes to NaN (Not a Number). This mostly results in motor disarm (depend on the application in the controller). This function can detect disconnected cable from the controller.

Safety example

In case of disconnection of any cable, GPIO value goes to the supply voltage or to GND. This malfunction results in NaN on the output of the ASC block.

ASC parameters

Name	Description
min	Low threshold of the input range
center	Center point of the input range. If this parameter is zero, the output is treated as unidirectional with a range from <0-1>.
max	High threshold of the input range
absmin	Input value under this threshold set output to NaN. *
absmax	Input value above this threshold set output to NaN. *
lpf	Output low-pass filter. More about lpf here.

*NaN typically do disarm

ASC states

Name	Description
in	Input signal to ASC block - usually [mV], value from GPIO input
out	Output signal from ASC block.

How to setup

Best approach to setup ASC is this:

1. In term type stop and press enter
   • With this, you override motor command and force it to freewheel
2. Go to ASC folder
3. Plot state in and out to scope into 2 plots
4. Move your input to low (potentiometer)
5. Write value from in to min parameter
6. Move your input to high
7. Write value from in to max
8. Now move with your input a check the output in scope