Microcontroller commands for MALT

This topic defines commands between the PC and the microcontroller (Arduino) that is controlling the sensors in the MALT. We recommended that the PC controlling the microcontroller is also the system or device under test (SUT/DUT).

Serial command interface

Communicate with the test rig via the following serial commands. Each command will write to and read from serial over a series of lines.

LIGHT light level

Adjusts the light level based on the given input.

The light panel used in the reference supports between .25 and 1.3 volts of input.

Using the data sheet for the reference DAC Microchip MCP4821, we can solve for the maximum Vout to send to the light panel.

1.3 = 2.048 * 1 * (D/(2^12))

D = 2600

Example:

The following example sends the voltage required to get the light at maximum brightness (based on formula above).

LIGHT 2600

Serial output:

Line 0
MALTERROR status code

READALSSENSOR sensor number

Sensor numbers are defined as follows:

1. Ambient Light Sensor (facing away from the screen)
2. Screen Light Sensor (facing toward the screen)

Example:

The following example writes the resulting raw data from the screen light sensor to serial. Lux can be calculated based on the datasheet of sensors used.

READALSSENSOR 2

Serial output:

Line 0	Line 1	Line 2
Exponent (0 on failure)	Result (0 on failure)	MALTERROR status code

READCOLORSENSOR sensor number

Sensor numbers are defined as follows:

1. Ambient Color Sensor (facing away from the screen)
2. Screen Color Sensor (facing toward the screen)

Example:

The following example writes the resulting data from the screen color sensor to serial. These numbers have gone through an onboard calibration matrix to be converted to the XYZ colorspace.

READCOLORSENSOR 2

Serial output:

Line 1	Line 2	Line 3	Line 4
X value	Y value	Z value	MALTERROR status code

CONVERSIONTIME conversion time in ms

The OPT3001 light sensors used in the reference support 2 conversion times: 800ms and 100ms. CONVERSIONTIME changes the conversion time of both sensors.

Note

If a measurement conversion is in progress when the configuration register is written, the active measurement conversion immediately aborts.

Example:

The following example changes the conversion time of both sensors to 100ms.

The default conversion time used by MALT prototype is 800ms.

CONVERSIONTIME 100

Serial output:

Line 0
MALTERROR status code

Unrecognized commands

For any unrecognized command:

Serial output:

Line 0
MALTERROR status code (where MALTERROR status code = E_UNRECOGNIZED_COMMAND)

MALT error code

E_SUCCESS	E_INVALID_PARAM	E_UNRECOGNIZED_COMMAND
0	1	2