max 1270

[huib]

Dear all,

At the monent I am working on a small project with uses an AD Converter MAX1270.

I have found different programs and schematic for this, but till now i was not able to get it working
If i look on the makers instruction i find a different layout than other on this forum

Can somebody indicates where i can find a (working) schema for the Max1270 with an bsxII

your assistance is highly appriciated

Regards

Huib

·

[PJ Allen]

The MAX1270 is used in the Stamp_PLC, but, uncharacteristically, there is no schematic of that product available.

A·"bsxII"?· Is that a Parallax product or some knock-off?

Provide details.

[huib]

No it is just a matter of typing to quick
It should have been BS2sx instead

however the question remains the same;

on certain schematic is mentioned that:
a) vdd / shdn to ground two (0.1 uF and 10 uF)
ref to ground one 4.7 uF
refadj to ground 0.1uF
b) vdd / shdn to ground one capacitor (0.1 uF)
ref to ground one 4.7 uF
refadj to ground 10 nF
and the 3rd
c) between shdn and cs a resistor of 4.7k
ref to ground 4.7 uF+
refadj to ground 0.1 uF
and from the makers MAXIM it looks like option b)

in all cases i get no data out of the max1270

(or did i just have killed the unit?)

so for that reason i was hoping to get a working schematic from somebody

kind regards
huib

[sam_sam_sam]

I look at the data sheet and it· look very much like the MAX186 in way you call up each channel
I just wrote a Demo code for it give this a try and let me know if this work
I order some free sample of the MAX1270 and I will them a try my self as well


·This table is the same for the MAX 186 part of what is posted below is from the MAX186 Data Sheet and
·the other part is from the MAX1270 Data Sheet
Table 2. Channel Selection
SEL2···· SEL1····· SEL0········ ·CHANNEL

····X···· X····· X
····· 0··········· 0··········· 0··············· ··········· CH0
····· 0·········· ·0··········· 1······················ ···· CH1
····· 0··········· 1············ 0·························· ·CH2
·····0············ 1············· 1······················ ·· CH3
···· 1·············0············ ·0······················ ·· CH4
··· ·1·············0············ ·1························· ·CH5
···· 1············· 1············ ·0······················ ·· CH6

·····1············· 1·············· 1······················· ··CH7



Bit 7···················· Bit 6···················· ·Bit 5··················· ·Bit 4··················· Bit3············· ·Bit 2·········· ·· Bit 1··········· Bit 0

(MSB)············································· ·················································· ·················································· ····················· (LSB)

START·············· SEL2····················· SEL1·············· SEL0··················· ·UNI/BIP··········SGL/DIF···· ··· ·PD1········· PD0

Bit················· Name··················· ·Description

7 (MSB)········· START··············· The first logic "1" bit after CS goes low defines the beginning of the control byte.

6····················· SEL2··················· These three bits select which of the eight channels are used for the conversion.

5····················· SEL1·················· ·See Tables 3 and 4.

4··················· SEL0

3················· UNI/BIP············ 1 = unipolar,······ ·0 = bipolar.······ Selects unipolar or bipolar conversion mode. In unipolar

················································· mode, an analog input signal from 0V to VREF can be converted; in bipolar mode, the

················································· signal can range from -VREF/2 to +VREF/2.

2············· ·SGL/DIF·············1 = single ended,··· ·0 = differential. Selects single-ended or differential conversions. In

·················································· single-ended mode, input signal voltages are referred to AGND. In differential mode,

················································· the voltage difference between two channels is measured. See Tables 3 and 4.

1·············· ··PD1························· Selects clock and power-down modes.

0(LSB········PD0·································· ······ PD1···················· PD0························ Mode

·················································· ·················· 0·························· 0····························· Full power-down (IQ = 2μA)· works

·················································· ·················· 0························ · 1····························· Fast power-down (IQ = 30μA) works

·················································· ·················· 1··························· 0···························· Internal clock mode· works

·················································· ·················· 1··························· 1·····························External clock mode

·················································· ·················· ^····························· ^····························· ^· This mode dose not work



Example: Simple Software Interface

Make sure the CPU’s serial interface runs in master

mode so the CPU generates the serial clock. Choose a

clock frequency from 100kHz to 2MHz.

1) Set up the control byte for external clock mode, call

it TB1. TB1 should be of the format: 1XXXXX(11··<<<<........ Look at the table·^^ Above ^^·for )

Binary, where the Xs denote the particular channel

and conversion-mode selected.

···································CHANNELs····· unipolar··· single ended

············· START············ ·· ·· SEL0· SEL1··SEL2·········UNI/BIP··· SGL/DIF······ ···· ·PD1·················PD0························
· [%·· 1········· ·X· X· ·X······ ·1···· · ·1············ ·0······· ·1· ]···Fast power-down



DO
· LOW CS················································ ············ ··' Enable ADC
· SHIFTOUT DataIn, Clock, MSBFIRST, [%10001101]···· ·' Select CH0, Single-Ended [%1XXX1101]
· SHIFTIN DataOut, Clock, MSBPOST, [result0\12]········ ' Read ADC
· HIGH CS················································ ··············' Disable ADC
· mVolts0 = result0 */ Cnts2Mv·································' Convert To Millivolts



·Please Let me know if this help




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Sam

Post Edited (sam_sam_sam) : 11/27/2009 2:37:59 AM GMT