In car multigauge

What are you developing?
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BennehBoy
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Re: In car multigauge

Post by BennehBoy » Tue Mar 14, 2017 12:50 pm

Forked Mux154 library with clear() method added -> https://github.com/BennehBoy/MUX154
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BennehBoy
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Re: In car multigauge

Post by BennehBoy » Tue Mar 14, 2017 5:03 pm

Does SPI require termination resistances?

The reason I ask is that if my MAX31856 is in circuit (which is just soldered to a TSSOP to DIP adapter), then SD fails to work.

Remove the MAX and all is well - could it be that I've neglected to do something obvious with my implementation? resistances to ground etc at the device end?
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zmemw16
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Re: In car multigauge

Post by zmemw16 » Tue Mar 14, 2017 5:10 pm

check your soldering ?
using the same /cs line ? yeah i know :)
does the MAX31856 work if SD is removed ?
stephen

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BennehBoy
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Re: In car multigauge

Post by BennehBoy » Tue Mar 14, 2017 5:47 pm

Hmm, I think this may have been a reflection issue of some sort, looking closer at the wiring I had something resembling a star topology...

All the OLED screens were hooked up along one spur of the bus, then there was a run of cable from the SPI pins out to the MAX, and then another run out to the SD card.

I've now hung the MAX off the end of the cable run to the SD card and it's working fine. Move it back and it fails.

Live and learn.
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zmemw16
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Re: In car multigauge

Post by zmemw16 » Tue Mar 14, 2017 7:29 pm

what happens now if you swap the MAX and SD (now on the same spur correct) ?
srp

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RogerClark
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Re: In car multigauge

Post by RogerClark » Tue Mar 14, 2017 7:39 pm

from what I have read, using a star topology can cause problems. Daisy chain is probably better

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BennehBoy
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Re: In car multigauge

Post by BennehBoy » Tue Mar 14, 2017 9:41 pm

zmemw16 wrote:what happens now if you swap the MAX and SD (now on the same spur correct) ?
srp
I'll try tomorrow, the max is on a TSOP14 to DIP adapter with wires hard soldered - I'm going to remove the wires and fit headers so I can reduce all the cable lengths.
RogerClark wrote:from what I have read, using a star topology can cause problems. Daisy chain is probably better
Yup, I read the same and then slapped my forehead.
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zmemw16
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Re: In car multigauge

Post by zmemw16 » Wed Mar 15, 2017 2:54 pm

what you like with I2C1?
i either get a hang with the Wire examples or every address is a device

stephen

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BennehBoy
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Re: In car multigauge

Post by BennehBoy » Wed Mar 15, 2017 3:56 pm

I2C is working fine for me.

I've got 2 devices on the same bus, an ADXL345, & an HMC5883.
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BennehBoy
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Re: In car multigauge

Post by BennehBoy » Wed Mar 15, 2017 4:10 pm

Although I made a £7 mistake today, forgot the max31856 is not 5v tolerant and fried it with an Arduino Nano :(

Luckily I've got 3.
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