Spider, Spi socket and MCP4131

Archive
1

Hi all. I got a strange problem again with the mcp4131 module.
At first I plugged the mcp4131 using the extender module into socket 9 (s type) and invoked the constructor:


SPI.Configuration MCP4131_Config = new SPI.Configuration((Cpu.Pin)GHI.Hardware.EMX.Pin.IO46, false, 0, 0, false, true, 800, SPI.SPI_module.SPI1);

SPI MCP4131_SPI = new SPI(MCP4131_Config);

And everything worked fine. I wanted to use socket 6 (S type as well) for the same module I plugged the extender to socket 6 and changed the code to:


SPI.Configuration MCP4131_Config = new SPI.Configuration((Cpu.Pin)GHI.Hardware.EMX.Pin.IO18, false, 0, 0, false, true, 800, SPI.SPI_module.SPI2); //IO18 is Pin number 3 at socket 6 according to schematics

SPI MCP4131_SPI = new SPI(MCP4131_Config);

But this time It won’t work. Any suggestion ? Is it possible to control 2 spi modules ?
Thanks in advance.

2

How exactly it doesn’t work?

3

@ Architect - Hi, thanks for replying.
The output is as follow:
i=128
Wiper REG: 0
Status REG: 0
TCON: 0
i=127
Wiper REG: 0
Status REG: 0
TCON: 0

and the resistance shows 157 ohm steady.

4

Is it the same mcp4131 that worked on the other socket?

5

@ Architect - Yeah, If I return the extender to socket 9 and invoke the first constructor, It works again.

6

Ok you need to have one SPI instance and switch SPI.Configuration for each IC when you need to access it.

7

@ Architect - I think i’m doing it already:



if (socketNumber == 9)
{
             MCP4131_Config = new SPI.Configuration((Cpu.Pin)GHI.Hardware.EMX.Pin.IO46, false, 0, 0, false, true, 800, SPI.SPI_module.SPI1);
 }
if (socketNumber == 6)
{
             MCP4131_Config = new SPI.Configuration((Cpu.Pin)GHI.Hardware.EMX.Pin.IO18, false, 0, 0, false, true, 800, SPI.SPI_module.SPI2);
}

MCP4131_SPI = new SPI(MCP4131_Config);

Is that what you mean?

8

more like

Config1 = new …
Config2 = new …

MCP_SPI = new SPI(Config1)

at this point SPI is connected to the first sensor.

When you need to talk to the second one you need to switch configuration:

MCP_SPI.Config = Config2

That is if you want to use both in your application. If you are using only one then your code should work.

9

@ Architect - Let’s go back to basic. I don’t wish to use socket 9.

Constructor at mcp4131.cs ->

 

      public MCP4131(Cpu.Pin cs_pin, SPI.SPI_module mod)
        {
            MCP4131_Config = new SPI.Configuration(cs_pin, false, 0, 0, false, true, 800, mod);
            MCP4131_SPI = new SPI(MCP4131_Config);
        }

Invoked with:


MCP4131 myMCP4131 = new MCP4131((Cpu.Pin)GHI.Hardware.EMX.Pin.IO18, SPI.SPI_module.SPI2);

And again, Plugged it to socket 6 (Lets forget about socket 9 right now), but the resistance stuck on low and won’t change, but you know, at the beginning, (before deploying the code) the resistance shows ~5k but afterwards it drops to 150 ohm steady, what’s your opinion? (the same code works fine with socket 9 using IO46 and spi1)

10

Maybe the socket is corrupted ? Is there any way the check that?

11

Do a visual examination first. Then try a logic analyzer to see that SPI lines are live.

You can also use a LED to check that each pin on that socket works as digital output.

12

@ Architect - Great idea! I connected led7r, every one of the leds except D5 turned on,
I guess the socket is corrupt. What’s next?
(Any idea how to fix this…)

13

Check if there is a short.

14

@ Architect - I’m not sure where to check, nothing is connected to the mainboard. I’ll open a new topic, thanks for all your help.

15

It is possible that you have damaged the pin when you had your IC laying on the conductive material.

If you have another Spider around I would check that first.