MAX1280EVC16 - Maxim Integrated Products, Inc.

Recommended Equipment

Before you begin, gather the following equipment:

•Maxim MAX1280EVC16 (contains MAX1280EVKIT

board and 68HC16MODULE-DIP)

•A small DC power supply, such as a 12VDC,

0.25A plug-in transformer, or a 9V battery

•An IBM PC-compatible computer running

Windows 95/98

•A spare serial communications port, preferably a

9-pin plug

•A serial cable to connect the computer’s serial

port to the 68HC16MODULE-DIP

General Description

The MAX1280 evaluation system (EV system) is a com-

plete, 8-channel data-acquisition system consisting of a

MAX1280 evaluation kit (EV kit) and a Maxim

68HC16MODULE-DIP microcontroller (µC) module. The

MAX1280 is a high-speed, multichannel, 12-bit data-

acquisition system. Windows 95/98®software provides

a handy user interface to exercise the MAX1280’s fea-

tures.

Order the complete EV system (MAX1280EVC16) for a

comprehensive evaluation of the MAX1280 using a PC.

Order the EV kit (MAX1280EVKIT) if the 68HC16MOD-

ULE-DIP module has already been purchased with a

previous Maxim EV system, or for custom use in other

µC-based systems.

Features

♦Proven PC Board Layout

♦Convenient On-Board Test Points

♦Data-Logging Software

♦Fully Assembled and Tested

Evaluates: MAX1280

MAX1280 Evaluation System

________________________________________________________________ Maxim Integrated Products 1

19-1625; Rev 0; 1/00

EV System Component List

PART

MAX1280EVKIT

MAX1280EVC16 0°C to +70°C

0°C to +70°C

TEMP. RANGE INTERFACE TYPE

User-supplied

Windows software

For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.

For small orders, phone 1-800-835-8769.

Ordering Information

Maxim MAX1280BCUP (20-pin TSSOP)1

8-pin header1TP1

10Ω±1% resistors2R9, R10

300Ω±5% resistors8R1–R8

3-pin header1JU2

2-pin header1JU1

REFERENCE

2x20 right-angle socket1J1

10µF, 10V tantalum capacitors2C12, C14

0.1µF ceramic capacitors2C11, C13

4.7µF, 10V tantalum capacitor1C9

0.01µF ceramic capacitors9C1–C8, C10

DESCRIPTIONQTY

PART

68HC16 µC module168HC16 MODULE-DIP

MAX1280 EV kit1MAX1280EVKIT

DESCRIPTIONQTY

None 1 PC board, MAX1280 EV kit

None 1 3 1/2in software disk, MAX1280 EV kit

None 1 MAX1280 EV kit data sheet

None 1 MAX1280 data sheet

FILE

Application programMAX1280.EXE

Installs the EV kit files on user’s

computer

INSTALL.EXE

DESCRIPTION

KIT1280.C16 Software loaded into 68HC16 µC

Note: The MAX1280 software is designed for use with the com-

plete MAX1280EVC16 EV system (includes 68HC16MODULE-

DIP module together with MAX1280EVKIT). If the MAX1280 eval-

uation software will not be used, the MAX1280EVKIT board can

be purchased by itself, without the µC.

Windows 95/98 is a registered trademark of Microsoft Corp.

EV Kit Component List

EV Kit Software Files

Evaluates: MAX1280

MAX1280 Evaluation System

2 _______________________________________________________________________________________

Connections and Setup

1) Carefully connect the boards by aligning the 40-pin

header of the MAX1280 EV kit with the 40-pin con-

nector of the 68HC16MODULE-DIP module. Gently

press them together. The two boards should be

flush against one another.

2) Ensure that JU1 is closed and JU2 is in the 1-2

position.

3) Connect a 7VDC to 20VDC power source to the µC

module at the terminal block located next to the

on/off switch, along the top edge of the µC module.

Observe the polarity marked on the board.

4) Connect a cable from the computer’s serial port to

the µC module. If using a 9-pin serial port, use a

straight-through, 9-pin female-to-male cable. If the

only available serial port uses a 25-pin connector, a

standard 25-pin to 9-pin adapter will be required.

The EV kit software checks the modem status lines

(CTS, DSR, DCD) to confirm that the correct port

has been selected.

5) Install the MAX1280 EV kit software on your com-

puter by running the INSTALL.EXE program on the

floppy disk. The program files are copied and icons

are created for them in the Windows Start menu.

6) Start the MAX1280 program by opening its icon in

the Start menu.

7) The program will prompt you to connect the µC

module and turn its power on. Slide SW1 to the ON

position. Select the correct serial port, and click

OK. The program will automatically download

KIT1280.C16 to the module.

8) Apply an input signal between analog common

(COM) and input channel CH0. Observe the read-

out on the screen.

Detailed Description

MAX1280 Stand-Alone EV Kit

The MAX1280EVKIT provides a proven PC board layout

to evaluate the MAX1280. It must be interfaced to

appropriate timing signals for proper operation.

Connect +5V to VDD1 and VDD2, and connect the

ground return to GND. See the MAX1280 EV kit

schematic (Figure 1). Refer to the MAX1280 data sheet

for timing requirements.

MAX1280 EV System

The MAX1280EVC16 EV system operates from a user-

supplied 7VDC to 20VDC power supply. Windows

95/98 software running on an IBM PC interfaces to the

EV system board through the computer’s serial commu-

nications port. See the Recommended Equipment and

Connections and Setup sections for setup and operat-

ing instructions.

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.

If the QSPI™ clock is set to STOP, then configuration

data will not be sent until the READ button is clicked.

Statistics

The Minimum and Maximum fields show the highest

and lowest readings acquired. The Average field shows

a running mean based on the equation ai= (k)(xi) +

(1 - k)(ai-1). The Clear button resets the statistics. To

remove 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.

QSPI is a trademark of Motorola, Inc.

Evaluating Shutdown

The evaluation software configures the 68HC16’s QSPI

submodule to continuously read data from the

MAX1280 into the 68HC16. The sample rate is con-

trolled by the QSPI clock. To evaluate power-saving

modes, these automatic updates must be stopped.

First, set the QSPI clock control to STOP. This reconfig-

ures the 68HC16’s QSPI submodule to stop driving the

serial clock. Second, in the evaluation software’s main

window, uncheck the “Read Every...msec” checkbox.

Next, choose the desired software power-down control

word, and click the Read button to send the new con-

figuration to the MAX1280. Or, if evaluating the hard-

ware shutdown, move jumper JU2 to the 2-3 position.

Sense the supply current by measuring the voltage

across resistors R9 and R10.

Reference Voltage

The evaluation software assumes a 2.5V reference volt-

age, unless otherwise specified. Refer to the MAX1280

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.

Description of Hardware

U1, the MAX1280, is a high-speed, multichannel, 12-bit

data-acquisition system. Resistors R1–R8 and capaci-

tors C1–C8 form single-pole, lowpass anti-aliasing fil-

ters with a nominal 3ms time constant and approxi-

mately a 50kHz corner frequency. Jumper JU1 con-

nects the analog common (COM) to ground (GND).

C10 bypasses the bandgap reference, and C9 bypass-

es the analog-to-digital converter’s (ADC’s) voltage ref-

erence. When plugged into the 68HC16MODULE,

VDD1 and VDD2 are both powered by +5V. See the

MAX1280 EV kit schematic (Figure 1) and refer to the

MAX1280 data sheet.

Measuring Supply Current

Power-supply current can be monitored by measuring

the voltage across resistor R9 (for VDD1) or R10

(VDD2). These resistors are 10Ω±1%, so every 0.001V

across R9 represents 100µA of supply current.

Troubleshooting

Problem: No output measurement. System seems to

report zero voltage or fails to make a measurement.

1) Check VDD1 and VDD2 supply voltages.

2) Check the 2.5V reference voltage using a DVM.

3) Verify with an oscilloscope that the conversion-start

signal is being strobed.

4) Verify that SHDN is being driven high.

Problem: Measurements are erratic, unstable; poor

accuracy.

1) Check the reference voltage using a DVM.

2) Use an oscilloscope to check for noise. When prob-

ing for noise, keep the oscilloscope ground return

lead as short as possible, preferably less than 1/2in

(10mm).

Evaluates: MAX1280

MAX1280 Evaluation System

_______________________________________________________________________________________ 3

JUMPER POSITION FUNCTION

Closed* COM is connected to GND.

1-2* Operate

JU2

2-3 Shutdown

Table 1. Jumper Functions

*Default configuration

Open

COM is disconnected from GND.

All analog inputs, including

COM, must still be within the

MAX1280’s common-mode

input range.

JU1

Evaluates: MAX1280

MAX1280 Evaluation System

4 _______________________________________________________________________________________

MAX1280

300Ω

0.01µF

CHO

VDD1

300Ω

0.01µF

CH1

VDD2

300Ω

0.01µF

CH2

SCLK

300Ω

0.01µF

CH3

300Ω

0.01µF

CH4

DIN

300Ω

0.01µF

CH5

SSTRB

300Ω

0.01µF

CH6

DOUT

300Ω

0.01µF

CH7

GND

COM

REFADJ

10 11

REF

JU2

VDD1

JU1 2

SHDN

J1-7

C13

0.1µF

R10

10Ω

C14

10µF

10V

TP1-7

J1-8

VDD2

C11

0.1µF

10Ω

C12

10µF

10V VDD1

VDD1

TP1-6

J1-37

TP1-4

J1-36

TP1-5

J1-31

J1-38

TP1-3

J1-29

TP1-2

J1-35

REF

4.7µF

10V

REFADJ

C10

0.01µF

GND

TP1-1

J1-1

J1-2

J1-3

J1-4

Figure 1. MAX1280 EV Kit Schematic

Evaluates: MAX1280

MAX1280 Evaluation System

_______________________________________________________________________________________ 5

Init: LDAA #$08 ; CS high, clock low by default

STAA QPDR

LDAA #$0F

STAA QPAR ; pins that are assigned to the QSPI

LDAA #$0E

STAA QDDR ; QSM pins that are outputs

LDAA #$80 ; CRCONT

STAA CR0 ; send eight-bit control word, and continue...

STAA CR2

STAA CR4

...

STAA CRE

LDAA #$40 ; (CRBITSE)

STAA CR1 ; receive sixteen-bit data field

STAA CR3

STAA CR5

...

STAA CRF

CLRD ; send zero when receiving data

STD TR1

STD TR3

STD TR5

...

STD TRF

LDAB #%10001111 ; channel 0, unipolar, single-ended, pd=11

std TR0 ; channel 0 command

ldab #$40 ; channel 1 bit mask

ord TR0

std TR2 ; channel 1 command

ldab #$10 ; channel 2 bit mask

ord TR0

std TR4 ; channel 2 command

...

ldab #$70 ; channel 7 bit mask

ord TR0

std TRE ; channel 7 command

CLR SPCR3 ; disable QSPI halt mode interrupt

LDD #$8008 ; BITS=16, SPBR=8 (1.049 MHz), CPOL=0, CPHA=0

STD SPCR0

LDD #$0204 ; DSCK, DTL not used

STD SPCR1

LDD #$4F00 ; newqp=0, endqp=15, wrap to zero

STD SPCR2 ; run QSPI continuously on all channels

BSETW SPCR1,#$8000 ; start the QSPI

BCLR SPSR,#$80 ; clear SPIF bit

ReadLoop:

LDD RR1

jsr Process_Channel_0

LDD RR3

jsr Process_Channel_1

LDD RR5

jsr Process_Channel_2

...

LDD RRF

jsr Process_Channel_7

jmp ReadLoop

Example 1. Reading All Channels with QSPI

Evaluates: MAX1280

MAX1280 Evaluation System

6 _______________________________________________________________________________________

Init: LDAA #$08 ; CS high, clock low by default

STAA QPDR

LDAA #$0F

STAA QPAR ; pins that are assigned to the QSPI

LDAA #$0E

STAA QDDR ; QSM pins that are outputs

LDAA #$80 ; CRCONT

STAA CR0 ; send eight-bit control word, and continue...

LDAA #$40 ; (CRBITSE)

STAA CR1 ; receive sixteen-bit data field

CLRD ; send zero when receiving data

STD TR1

LDAB #%10001111 ; channel 0, unipolar, single-ended, pd=11

std TR0 ; channel 0 command

CLR SPCR3 ; disable QSPI halt mode interrupt

LDD #$8008 ; BITS=16, SPBR=8 (1.049 MHz), CPOL=0, CPHA=0

STD SPCR0

LDD #$0204 ; DSCK, DTL not used

STD SPCR1

LDD #$0100 ; newqp=0, endqp=1, no wrap

STD SPCR2

ReadLoop:

BSETW SPCR1,#$8000 ; start the QSPI

BCLR SPSR,#$80 ; clear SPIF bit

Idle: BRCLR SPSR,#$80,Idle ; wait util SPIF bit is set

LDD RR1

ROLD

jsr Process_Channel_0

jmp ReadLoop

Example 2. Reading a Single Channel with QSPI

Evaluates: MAX1280

MAX1280 Evaluation System

_______________________________________________________________________________________ 7

Figure 2. MAX1280 EV Kit Component Placement Guide—

Component Side

1.0"

Figure 3. MAX1280 EV Kit PC Board Layout—Component Side

1.0"

Figure 4. MAX1280 EV Kit PC Board Layout—Solder Side

1.0"

Evaluates: MAX1280

MAX1280 Evaluation System

8 _______________________________________________________________________________________

NOTES