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AN-744

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AN-744

RESET pin on the ADuC7026 is Schmitt-triggered inter-
nally there is no need to use an external Schmitt trigger 
on this pin.
When  inserted  the  IRQ0  push-button  switch  drives 
P0.4/IRQ0 high. This can be used to initiate an external 
interrupt 0.
To enter serial download mode the user must pull the 
P0.0/BM pin low while reset is toggled. On the evalua-
tion board, serial download mode can be easily initiated 
by holding down the serial download push-button (S2) 
while  inserting  and  releasing  the  reset  button  (S3)  as 
illustrated in Figure 1.

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Figure 1. Entering Serial Download Mode 
on the Evaluation Board

Power Indicator/General-Purpose LEDs

A red power LED (D3) is used to indicate that a sufficient 
supply is available on the board. A general-purpose LED 
(D2) is directly connected to P4.2 of the ADuC7026. When 
P4.2 is cleared the LED will be turned on, and when P4.2 
is set, the LED will be turned off.

Analog I/O Connections

All analog I/O are brought out on header J3.
ADC0 and ADC1 are buffered using an AD8606 to evaluate 
single-ended and pseudo differential mode. A potentiometer 
can be connected to ADC0 buffered.
ADC3 and ADC4 can be buffered with a single-ended to 
differential op amp on board, the AD8132, used to evalu-
ate the ADC in fully differential mode.
ADC2 and ADC5 to ADC11 are not buffered. Be sure to 
follow the data sheet recommendation when connecting 
signals to these inputs.
DAC1 can be used to control the brightness of the green 
LED D1, when connected via the S1 switch.

General-Purpose Prototype Area

General-purpose  prototype  areas  are  provided  at  the 
bottom  of  the  evaluation  board  for  adding  external 
components as required in the user’s application. As can 
be seen from the layout AV

DD

, AGND, V

DDIO

, and DGND 

tracks are provided in this prototype area.

External Memory and Latch Footprint

Footprint for a 32 kB 

 16 static RAM (CY7C1020CV33) 

and 16-bit latch is also on board. See External Memory 
Interface section.

DIP SWITCH LINK OPTIONS
S1-1 VREF

Function:   Connects the output of the 2.5 V external refer-

ence (ADR291) to the VREF pin (Pin 55) of the 
ADuC7026.

Use:           Slide S1-1 to the on position to connect the 

external reference to the ADuC7026.
Slide S1-1 to the off position to use the internal 
2.5 V reference or a different external reference 
on VREF pin of J3 header.

S1-2 VOCM

Function:   Connects 1.67 V to the V

OCM

 pin of the AD8132. 

No extra dc voltage is required on the board 
to use the ADC in differential mode.

Use:           Slide S1-2 to the on position to connect V

OCM

 

of the differential amplifier to 1.67 V, divided 
output of the ADR291 reference.
Slide S1-2 to the off position to use a different 
voltage for V

OCM

 by connecting a dc voltage to 

the V

OCM

 pin of J3 header. Note that V

OCM

 value 

is  dependent  on  reference  value  as  shown  in 
Table 1.

Table 1. V

OCM

 Range

V

REF

                           V

OCM

 min 

V

OCM

 max

2.5 V                           1.25 V 

2.05 V

2.048 V                       1.024 V 

2.276 V

1.25 V                         0.75 V 

2.55 V

S1-3 POT

Function:   Connects the potentiometer output to ADC0. 

This input is buffered by an AD8606. This is 
for demonstration purposes.

Use:           Slide S1-3 to the on position to connect the 

potentiometer to the op amp of ADC0 input 
channel.
Slide  S1-3  to  the  off  position  to  use  ADC0 
input on J3 header.

S1-4 ADC3

Function:   Brings out ADC3 (Pin 64) on J3 header.
Use:           Slide  S1-6  to  the  on  position  to  connect

directly  ADC3  of  J3  header  to  ADC3  pin 
(Pin 64) of the ADuC7026.
Slide S1-6 to the off position to disconnect 
ADC3 of J3 header from ADC3 pin (Pin 64) of 
the ADuC7026.

REV. 0

REV. 0

Содержание ADuC7026

Страница 1: ...ctly to the digital section and is filtered before being routed into the analog section of the board FEATURES Power Supply The user should connect the 9 V power supply via the 2 1 mm input power socke...

Страница 2: ...external components as required in the user s application As can be seen from the layout AVDD AGND VDDIO and DGND tracks are provided in this prototype area External Memory and Latch Footprint Footpr...

Страница 3: ...C1 output to D1 Slide S1 7 to the off position to use DAC1 output on J3 header EXTERNAL CONNECTORS J3 Analog I O Connector The analog I O connector J3 provides external connections for all ADC inputs...

Страница 4: ...2 18 P2 7 PWM1L MS3 J2 19 P3 7 PWMSYNC AD7 PLAI 15 J2 20 P3 6 PWMTRIP AD6 PLAI 14 J2 21 P0 7 ECLK SIN PLAO 4 Pin Number Pin Description J2 22 P2 0 CONV SOUT PLAO 5 J2 23 P0 5 IRQ1 ADCBUSY MS0 PLAO 2 J...

Страница 5: ...any memory interface MSO memory select is connected to CE to enable the memory only when necessary BHE and BLE allow the user to select the high or low byte of the 16 bit memory Data 16 bits of data A...

Страница 6: ...e sample code in adc pot c the variation in the potentiometer resistance can be seen on the output LED Note that the internal and external references are 2 5 V which gives an ADC input range of 0 V to...

Страница 7: ...7 AN 744 SCHEMATIC Figure 4 ADuC7026 Evaluation Board Schematic REV 0...

Страница 8: ...8 AN 744 Figure 5 ADuC7026 Evaluation Board Silkscreen REV 0...

Страница 9: ...tch D1 D2 D3 3 LED 1 8 mm miniature LED 515 620 Farnell D4 1 PRLL4002 Diode BAV103DITR ND Digi Key C1 C5 C13 C15 C18 C22 C23 7 10 F Surface mount tantalum cap 197 130 Farnell Taj B case C2 C4 C6 C12 C...

Страница 10: ...R21 R22 R24 3 100 k Surface mount resistor 911 471 Farnell 0603 case L1 1 Ferrite bead Surface mount inductor 581 094 Farnell 1206 case J1 1 4 pin header 4 pin 90 single row header TSM 104 02 T SH Sa...

Страница 11: ...11...

Страница 12: ...respective owners Purchase of licensed I2 C components of Analog Devices or one of its sublicensed Associated Companies conveys a license for the purchaser under the Philips I2 C Patent Rights to use...

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