Reference Adjustment

The MAX186 software assumes a reference voltage of

4.096V. This value is used for calculating the displayed

results after each conversion. The value can be altered

to reflect the exact reference voltage of the MAX186 or

to scale the displayed readings. Changing the indicated

value does not alter the MAX186’s reference voltage.

The MAX186’s internal 4.096V reference voltage can be

adjusted over a ±1.5% range by adding resistors R10

through R13, shown on the schematic. Refer to the

MAX186 data sheet for detailed information about the

reference voltage.

Description of Software

The evaluation software’s main window controls the

active control word bits, serial clock speed, and sam-

ple rate. It displays the voltage and output code for

each active channel, as well as some statistics of the

input signal. A separate graph window shows the data

changing in real time. The update rate is limited to

about 10 samples per second due to COM port band-

width limitations.

Controls

The control word is divided into several fields. To

change the active control word, drop down the appro-

priate field’s combo box and select the desired option.

Statistics

The Minimum and Maximum fields show the highest and

lowest readings acquired. The Average field shows a run-

offset errors, first apply 0V to the active input channel,

clear statistics, acquire some samples, and then check

Tare. This average offset voltage will now be subtracted

from all subsequent measurements.

Sampling

Choose the desired sampling rate (QSPI Clock), sam-

pling size (Sample! menu item), click Begin Sampling!

(in Sample! pop-up window). Sample size is restricted

to a power of 2 to permit FFT processing once the data

is saved to a file. After the samples have been collect-

ed, the data is automatically uploaded to the host and

is graphed. Once displayed, the data can optionally be

saved to a file.

Saving Graphs to Disk

Data in the real-time graph and in sampled data graphs

may be saved to a file. Only the raw output codes are

saved, but voltages may be inferred, based on the ref-

erence voltage and the maximum code value.

Scanning All Channels

To scan through all channels, select SCAN from the

INPUT menu.

Reference Voltage

The evaluation software assumes a 4.096V reference

voltage, unless otherwise specified. Refer to the

MAX186 IC data sheet for more information. To override

this value, type the new reference voltage into the Vref

edit box and click the Set Vref button.

RAM Resident Program

The 186RAM.MAX program is an 80C32 program that is

transferred from disk to the static RAM on the 80C32

module. It receives conversion commands from the

186EVKIT program running on the personal computer,

controls the conversion cycle, and returns the results. Its

operation is transparent to the user.

EPROM Resident Program

In addition to the two programs supplied with the

MAX186 EV kit, a small 80C32 bootstrap program is

stored in the EPROM located on the 80C32 board. The

EPROM resident program initializes the 80C32, estab-

lishes communications over the RS-232 link, checks the

static RAM, and downloads the 186RAM program. Its

operation starts on power-up and whenever the reset

button is pressed. It transmits an identification banner

after receiving the first character and then tests the on-

board static RAM.

The last operation performed by the EPROM resident

program is downloading the 186RAM program and

storing it in the static RAM. Once the program is fully

loaded, control of the 80C32 is transferred to the RAM

resident 186RAM program.

MAX186 Evaluation System/Evaluation Kit

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