12 replies to this topic

[Stefan]

Hi, it's me, supernewbie ! I'm playing with my mini atm, and I decided to use TTL to debug and deploy. This works great, but I was hoping I could use pins 1 to 3 in my code as GPIO while deploying over TTL. Appairently this is not the case. Am I wrong, am I doing something wrong, please explain

[Mario Vernari]

Sorry, but...I suppose that "atm" stands for Netduino mini, and "TTL" for UART at TTL-level... If so, I don't mean the point at all...

[Nevyn]

I'm playing with my mini atm, and I decided to use TTL to debug and deploy. This works great, but I was hoping I could use pins 1 to 3 in my code as GPIO while deploying over TTL. Appairently this is not the case.

I think that pins 1-3 are reserved for RS232 only. You can switch to deploying/debugging over RS232 and this will free up pins 11 & 12.

Sorry, but...I suppose that "atm" stands for Netduino mini, and "TTL" for UART at TTL-level...

ATM = At The Moment

Hope tis helps,
Mark

[Chris Walker]

Advanced topic Actually, you can use pins 1-3 as GPIO (for pin 3, input only) if you use TTL for deploy/debug. However, they will be -5V/5V+ outputs (from the TTL-RS232 chip), not 0/3V3 outputs. And you'll need to reference them using (Cpu.Pin) casting, pulling their pin #s from the Netduino Mini schematic. Chris

[Nevyn]

Actually, you can use pins 1-3 as GPIO (for pin 3, input only) if you use TTL for deploy/debug. However, they will be -5V/5V+ outputs (from the TTL-RS232 chip), not 0/3V3 outputs. And you'll need to reference them using (Cpu.Pin) casting, pulling their pin #s from the Netduino Mini schematic.

Ooooooo - now I can see that being really handy to have access to.

Regards,
Mark

[Stefan]

Advanced topic

Ahhh, so it's actually not such a newb-question

I was thinking, when using TTL for deployment, I only use 2 pins instead of 3, so it saves 1 pin. Also, my laptop has no serial port and I have a TTL-to-USB-breakout.

The -5V to +5V could be interesting to play with, just as the input port. But not for my current project.

From http://www.netduino....i/schematic.pdf:

DRXD -> PA27
DTXD -> PA28
DTR -> PA29

Am I correct that they're (cpu.pin)27 to (cpu.pin)29 ?

[Chris Walker]

Am I correct that they're (cpu.pin)27 to (cpu.pin)29 ?

Precisely!

Also, be careful when using pin 29. The "DTR" pin -- (Cpu.Pin)29 -- is checked during boot. If it's active, then your Netduino Mini will go into bootloader mode It's available for your use in code...but only as an advanced hack

BTW, you might notice that you can't create an OutputPort with that pin. .NET MF automatically protects you

Chris

[Stefan]

Also, be careful when using pin 29. The "DTR" pin -- (Cpu.Pin)29 -- is checked during boot. If it's active, then your Netduino Mini will go into bootloader mode It's available for your use in code...but only as an advanced hack

BTW, you might notice that you can't create an OutputPort with that pin. .NET MF automatically protects you

Cool! Going to play with it some day, for my current project, I stay at RS232-deployment then. I want to keep as many pins available as possible.

[cys]

I know this is an old thread, but has anyone played with pins 1-3 [(cpu.pin)27 to (cpu.pin)29] for anything other than RS232 deployment?

[Stefan]

I've considered it, but because it outputs -5V to +5V (if I'm correct) I didn't found a good use for it. It is possible though, to drive them that way!

[cys]

I was hoping someone might have come up with an application for the +/-5V. I guess I'm going to try incorporating a sub-circuit on my pcb that converts rs232 to ttl.

I've considered it, but because it outputs -5V to +5V (if I'm correct) I didn't found a good use for it. It is possible though, to drive them that way!

[cys]

I'm working on using pins 1 and 2. I need one more pin for my project.

If I create an output port as: OutputPort _output = new OutputPort((Cpu.Pin)27, false); or OutputPort _output = new OutputPort((Cpu.Pin)27, true);, a DVM shows that nothing changes on pin 1 or pin 2. DRXD is shown on the schematic as "G3 PA27/PGMD15."

If PA27/DRXD is (Cpu.Pin)27, then what would then be the (Cpu.Pin) identity of PB27/ADO D9?

[Note added: Per a recent thread, PA references PIO controller A multiplexing and PB controller B multiplexing -- pages 31-33 of the ARM document.]

[cys]

In case anyone is interested, my mini project is a scuba diving computer that tracks decompression obligation, and controls a rebreather solenoid based on voting logic input from three oxygen sensors. I need one more pin to control the spi bus to use a flash memory chip (I understand that the new firmware will give access to flash, but I don't want to change firmware yet). Chris