Hi Chris,

Here are my settings:

static SPI.Configuration Device1 = new SPI.Configuration(                Pins.GPIO_PIN_D6,    // SS-pin                false,               // SS-pin active state                0,                   // The setup time for the SS port                0,                   // The hold time for the SS port                true,                // The idle state of the clock                true,                // The sampling clock edge                4000,                // The SPI clock rate in KHz                SPI.SPI_module.SPI1  // The used SPI bus (refers to a MOSI MISO and SCLK pinset)                );

So, I guess I should think about purchasing a scope. 

Chris

Update.

Homebrewed mini2:

Homebrewed mini2 in situ with project (the jumper is to optimize one of the four spi parts):

After more fiddling I have the spi pressure sensor functioning with workarounds. I made "init/coefficient load/pressure read" a combined method for every pressure sensor read, instead of "init/coefficient load" once upon power on, and then only "pressure read" subsequently, as with the program under 4.1 and based on the way the part is supposed to function. The "init/coefficient load" somehow stabilizes the "pressure read." Also, on power up I have to run "init/coefficient load/pressure read" three times before the pressure reading is made correctly. Due to some strange spi instability, the first two reads are always garbage. After the first two it's fine. I just implemented a counter to ignore the first two reads. So, my dive computer is now (more or less) moved from 4.1 over to 4.2/4.3. Phew...

I made some progress getting the 4th spi part to work on the move from 4.1 to 4.2/4.3. I was using an analog pin as chip select. When I used one of the other digital pins that helped somewhat -- the pressure sensor works immediately after a reset signal is sent... *most of the time*. This is strange behavior. Normally the reset is sent to the pressure sensor once upon power up, and then the pressure is read thereafter without any further need for resets (actually it's a reset and then read of coefficients for later pressure calcs). The kludge of reset/pressure read would be okay... However, the inconsistency where pressure is not read correctly say 10% of the time is not. I can see I would benefit from a scope. However, I won't go down that path unless the move to I2C doesn't pan out.

I've gone on to try the 4.3 beta firmware. No dice. I guess I'll move my boards over to I2C for the one part that spi is not functioning with.

If expense is no object, I get flexible 30 gauge wire from McMaster Carr, part no. [color=rgb(0,0,0);font-family:Arial, Helvetica, sans-serif;font-size:12px;text-align:center;]7071K151[/color]

I'm in the process of migrating my project over to the Plus 2 from a Netduino/mini. I've been able to get three of four spi devices working. Two devices worked straight away, and one needed some pauses added in the driver, presumably due to the faster chip. The fourth spi device is resisting all attempts to get it up and going. I've tried:

NetduinoPlus2_Firmware_4.2.2.2.dfu and NetduinoPlus2_Firmware_4.2.2.1.dfu,

speeds ranging from 1250 to 10000 KHz,

all combinations of idle state and sampling clock edge,

adding various setup and hold time pauses,

adding pauses to the driver.

The device is a pressure sensor that senses both pressure and temperature. With one parameter set I can see temperature being measured correctly about every third or fourth restart of the program, but pressure is never reported correctly. I don't have a scope. I would buy one if I thought it would get me through this. Other options are re-do two pcb's and try and get the pressure sensor up with I2C (my Plus 2 is a home brewed "mini 2") or give 4.3 beta a shot after biting the Windows 8/VS2012 bullet (right now running XP and VS2010; I have things I have to maintain under 4.1). Any thoughts/suggestions appreciated.

Chris

The minimum clock speed of the Netduino has been reported to be about 200 KHz. 

Also, 100 KHz may be too slow.

Your code may need lines to the following effect:

[color=#0000ff;]SPI SPI_Out = new SPI(Device1);[/color]

and then when you want to use device 2:

[color=#0000ff;]SPI_Out.Config = Device2;[/color]

back to device 1:

[color=#0000ff;]SPI_Out.Config = Device1;[/color]

I was able to install the Plus 2 firmware. The blinky app successfully deployed via usb. Below is a video clip of the blinky app in action. Kudos to Secret Labs for the simple and robust approach taken to install the firmware. I gave the other firmwares a shot (ghi, mountaineer) after swapping in the appropriate oscillator, but they were a no-go due to apparent usb driver issues/incompatibilities.

This instructable could be useful to someone: link.

Also, the first chapter of The Art of Electronics by Horowitz and Hill starts from no prior knowledge and covers the foundations.

As far as power beyond the Netduino pins, you can do a lot with cheap battery holders. Here is a 3 AA battery holder with a switch for less than $2: link. Cut a breadboard jumper wire in half and solder the two parts to the output wires on the battery holder and you have a nice breadboard power supply. Between parallel or serial battery configurations and alkaline or lithium ion batteries, it's possible to generate a lot of different voltages and capacities. Pololu is a good source for voltage regulators that are breadboard compatible. For example, with an input as low as 1.5 V, this regulator, here, can produce a 4-25V output and it's only about $10.

Based on experience with a project that started with a Netduino/breadboard and then moved to a Netduino mini/pcb's, consider starting out right away making whatever drew your interest to Netduino, no matter how complex it might be. Then, break that thing into pieces/sub-units that can be brought together incrementally, and just dig in to the project, learning and solving problems along the way.

I powered my breadboards and components (including a lcd display, solenoid, etc) by grabbing power from the Netduino 5V pins using jumper wires. If you are going to go the breadboard route, get a bunch of those wires. I picked up several kinds of cheap breadboards. Most of my initial parts I got from SparkFun. These days I get most things from Digikey.

A soldering iron can be handy even when doing stuff with breadboards as sometimes parts don't come with pins or you need to put your own breakout board together for a part. Any soldering iron will work for this. Keep in mind that flux beyond what may be in the solder wire is helpful. I started out with a $20 iron.

STM32F4 mini has been built. No testing yet, apart from that it didn't burn up when I attached the USB, and that I verified 5V is delivered to the 5V pin.

Yes, it's a tad wider for the time being. I know where to source the kind of pins found on the mini. I plan to revert to those pins after testing the board in its current format.

I modified the schematic from eleccelerator to arrive at a STM32F4 mini board in basic stamp 2 format. The voltage, ground and spi pins are in the same place as in the mini, a requirement for compatibility with my current project pcb (rebreather controller/dive computer). I'll build it and see if it works before too long. The layout is not as aesthetically pleasing as it might be. 

Thanks for posting the link. Very interesting and nicely implemented.

Chris

It's easy to make one, but maybe this breakout will help you?

https://www.sparkfun.../products/11978

Since the Cerb 40 firmware can be used on the [color=rgb(0,0,0);font-family:Arial, Helvetica, sans-serif;]STM32F4Discovery board with very minor modifications relating to the crystal speed, I'm guessing I could use the Netduino Plus 2 firmware to run an STM32F mini (a.k.a. DIY mini 2)... [/color]

If anyone can comment on issues that will come up using [color=rgb(0,0,0);font-family:Arial, Helvetica, sans-serif;]the .DFU firmware file on a DIY mini 2 ([/color][color=rgb(51,51,51);font-family:Verdana, Arial, Helvetica, sans-serif;]NetduinoPlus2_Firmware_4.2.1.2_00_08000000.bin, ER_CONFIG, and ER_FLASH[/color]), that would be appreciated.

[color=rgb(51,51,51);font-family:Verdana, Arial, Helvetica, sans-serif;]I would think there would be many people interested in a DIY mini 2? I haven't thought yet about fitting everything on the basic stamp 2 format board. The idea would be to keep it simple and not add any features (or as few as possible) beyond what is on the mini. For my application, I really just need the current mini pinout. If I had a pcb that extended further on either end of the board to accommodate extra needed components that would be fine.[/color]

i designed one, sadly i placed the sd card slot one, so i have to wait for the new pcb's where i fixed this..

 

 

https://www.dropbox....board_front.png

https://www.dropbox...._board_back.png

 

its a f405, was quite simple actually

it can run the netmf for stm32 port in codeplex.

(iam using it with native code tho)

 

 

edit: oh and theres the cerb40 allready aviable.

Thanks for the info, and nice pcb. I want to try and keep the basic stamp 2 compatibility.

I guess this is the stm32 port that you were mentioning, here: http://netmf4stm32.codeplex.com

Is an STM32F4 mini on the horizon? If not, I'd like to make one...

Chris