FVN.Net

Thanks but this doesn't get me any further. Does the '80' only apply to the address or also to the command byte?

This gives an error:

outbytes = New Byte() {80, 1, 1}
                IIC.WriteRead(outbytes, inbytes)

And this too:

outbytes = New Byte() {161, 1, 1}
                IIC.WriteRead(outbytes, inbytes)

If I split up the reading from the writing, I get beyond this just fine:

outbytes = New Byte() {80, 1, 1}
                IIC.Write(outbytes)

But then the exception is thrown right after when I try to read into 'inbytes':

A first chance exception of type 'System.ArgumentException' occurred in Microsoft.SPOT.Hardware.dll
Exception was thrown: System.ArgumentException

So it seems it goes bad when reading.

My problem is A) being new to Netduino and embedded in general, B ) never used I²C and C) not familiar with this particular device (RFID reader).
This means a lot of unknowns in the equation, and I don't know how to code up I²C straight from the µF in VB. Is my VB code bad or do I just send or expect the wrong things from the slave device?

For point B I try to use the Toolbox I2C-helper but I'm doing something wrong obviously.
For point C here's the device (+datasheet): http://www.stronglin...ules/sl030.html

I found some assembler-ish or C-like code samples to interface this device over I²C and hoped to understand it and 'translate' it to my needs but I must admit I don't really get what I'm seeing.

I'm hoping someone out here could show me the way or guide me through the learning process? I'd really appreciate that.
- Franki

EDIT: opened a new topic for this HERE since I think I made a breakthrough.

As a coincidence, I was trying about the same thing last night - and failed!
I'm trying to read the card ID from an RFID reader through I²C.

Here's my code:

Dim IIC As New MultiI2C(161, 100)
    Dim outbytes() As Byte = New Byte() {}
    Dim inbytes() As Byte = New Byte() {}
    
    outbytes = New Byte() {161, 1, 1}
    IIC.WriteRead(outbytes, inbytes)

I made an event handler based on the 'card detected' output, fed to an input. This works fine.
The last 2 lines of code are in the interrupt / event handler because it only makes sense to talk to the reader when a card is detected.

And here's where it crashes:
"A first chance exception of type 'System.ArgumentException' occurred in Microsoft.SPOT.Hardware.dll
Exception was thrown: System.ArgumentException"

Why 161: the datasheet says I need a 7 bit address (default = 80), and the 8th bit (LSB) should be '1' to read.
That gives: 10100001 = 161.

Why {161, 1, 1}: the specs say:

• Address: 1 byte, 0xA0
• Len: Byte length counting from Command Code to the last byte of the data, 1 byte.
• Command: Command Code, 1 byte.
• Data: Data, variable length depends on the command type.

So read from address 80 = 161, 1 byte length, command = 1

The question is: do I use the VB code in a wrong way, or don't I understand the specs of the I²C protocol?
I can't find any useful information online that combines N+ with VB and I²C. So I need to turn to this forum once again for help...

HELP!
- Franki

I finally got to test it and yes it sure works! Thanks!

Kem, PROBLEM SOLVED!

I just installed 'Version: 4.2.0 Update 1 (version 4.2.0.1)' of the firmware, I was still running 'NetduinoPlus_4.2.0.0_RC5' which I believed to be the most recent but it turned out Chris W published an update note yesterday. My bad!

My led is now blinking to the value of the potmeter. Finally!

Is there an online document or resource where I can get an overview of the most used classes for I/O (RS-232, I2C, SPI, PWM etc)? I'd love to learn more without having to ask too many questions, like I try to solve my Win Forms programming problems.

Thanks again for all your help!
- Franki

Dear Kem, I really appreciate your time and effort, but all your hints don't work for me (so far).
I opened a totally new solution from scratch. Even one single line of code causes the program to break:

Imports Microsoft.SPOT
Imports Microsoft.SPOT.Hardware
Imports SecretLabs.NETMF.Hardware
Imports SecretLabs.NETMF.Hardware.NetduinoPlus

Module Module1
    Sub Main()
        ' write your code here
        Dim potMeter As New AnalogInput(AnalogChannels.ANALOG_PIN_A1)
    End Sub
End Module

An attached PNG shows my references.
I just don't get it, it's always 'An unhandled exception of type 'System.ArgumentException' occurred in Microsoft.SPOT.Hardware.dll'and the execution breaks.

I wrote a button-lights-led program that works so it's really the AnalogInput part that bothers me.

- Franki