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Chapter 6: Test

Evaluation of all parts of the system has been developed on Engineering laboratory of

austriamicrosystems AG sited in Unterpremstätten (Austria).

a. Transmitter

The connection between every part of the transmitter side is shown in the figure 14

Figure 16

In this picture, shunt resistor is connected to the charge/discharge way to the battery and

to the current input (blue and yellow wires); and the voltage of it is connected to the voltage

input (yellow and black wires).

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With the help of one logic analyzer, the communication between AS8510 and

microcontroller can be tested as well as the communication through TWI interface between

microcontroller and AS3940 client demoboard.

The second one is shown in the screenshot 1

Screenshot 1

AS3940 client demoboard takes the control of the TWI bus and sends to the transmitter

board one read operation with the address 0x50 which is the address of transmitter

microcontroller. Following, microcontroller takes the bus control and transfers two bytes

which, in this case, are the hexadecimal value 0x0007. That means that the microcontroller is

sending one low value due to current input was short-circuited at the moment of the logic

analyzer capture. It is easy to see on this screenshot the proper work of ACK bit and, in

general, the TWI communication.

Next screenshot shows the frequency of the TWI interrupt which is given by the AS3940

client demoboard to get one new value to be sent via wireless.

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Screenshot 2

By the same way that the TWI communication, the transferring through SPI interface has

been tested and the result is shown in screenshot 3.

Screenshot 3

On the last screenshot, microcontroller is reading 4 bytes from the slave AS8510

corresponding to current and voltage measurement. Read registers are 0x00, 0x01, 0x02 and

0x03 like it is shown in the line MOSI of the screenshot 3. The values of these registers are

transferred through the line MISO from AS8510 to microcontroller. The transfers are

accomplished after the interrupt given for the AS8510 like is shown in line INT of screenshot 3.

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After those studies, it is easy to see that the function of transmitter board is being

performed properly and the transmission of the SOC estimation, current and voltage to

AS3940 client demoboard can be ensured.

b. Receiver

Next figure shows the complete system of the receiver side

Figure 17

The communication between AS3940 master demoboard and receiver board is alike than

TWI communication with transmitter board wherewith it has not been considered necessary

to be described again in order to not load the documentation with unnecessary repeated

information.

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In figure 18, the representation on the LCD display is shown.

Figure 18

c. Complete system

After evaluating both sides separately, figure 19 shows the whole system with both sides

working jointly.

Figure 19

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The wireless communication device AS3940 was configured to transfer packets every

250ms although the SOC algorithm is running each millisecond.

While testing the whole system, the behavior of the ADC converter AS8510 has not been

proper. Using the bypass for the amplifier, the function of the AS8510 was correct and the

device was working like it is supposed, but when the amplifier is active, the output of the

sigma-delta converter did not make sense. The measurements are shown like following

Gain = 100

Gain = 40

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Gain = 5

Comparing these resolutions with the theoretical ones calculated on page 33, it is easy to

see that the amplifier is not working properly because the value of the resolution is not even

the same order of magnitude. Furthermore, a small offset about 2 or 3 LSB can be expected in

the binary output; but, in this case, the huge difference with zero binary output confirms the

wrong behavior of the amplifier and, therefore, the device was broken at the moment of

evaluation. Another reason to can be sure that this device was broken is the no-difference

between the resolutions with the difference gain possibilities.

This observation was confirmed too late to be ordered, delivered, replaced and evaluated

on the system. Anyway, the programming of the microcontroller has been performed

expecting the right behavior of the converter on the first small current range with gain of 100.