Need single, low-speed, digital output pin on EMC2

[Ananya.Muddukrishna]

Hi,

I need a single, low-speed, digital output pin on EMC2 to communicate with an external microcontroller. The interface to this pin should preferably be simple. Such pins are available on the Rasberry Pi or the Beaglebone Black for general purpose I/O.

Is such a pin available on the EMC2?

I was unable to find a good answer to this in the documentation. The TTL I/O port, the 1-device port, and the RS232 port (underneath) are good alternatives but I would like a confirmation from you.

Best regards,
Ananya

[Timoteo]

Hi,
Are there general purpose I/O pins on the EMC2?

I need a single digital output pin to communicate with an external microcontroller.

Best regards,

Ananya

Hi Ananya,

Which kind of physical connection would you do? If you just need "pins", you could try with the LVTTL (JP3). If you have material to use it, another thing you could try, is disconnect the SEIC extension, and use pins from there (J4).
If you have SMA cables, you can use the 2 SMA outputs at the SEIC
extension. (A1,A2)

Give me details of how you would connect your output pin, and I can
think of a solution

Timoteo

Hi Timoteo,

I just a single pin that puts out logic high when a program starts running and logic low when the program finishes.

An external microcontroller will sense changes on this pin and take power measurement actions.

I want to be able to set/reset this pin easily from the program and would prefer a simple female-to-female wire connection to the microcontroller.

Best regards,
Ananya

Which kind of female to female? What I mean is, the microcontroller you want to interact with, is it on a specific board, or you are using a protoboard, etc?
Im thinking about how to connect it.

In case you can use SMA, you could use A1 from the SEIC:

1.jpg (617.83 KiB) Viewed 7572 times

Regards,
Timoteo

This is the female-to-female wire I have in mind.
https://www.kjell.com/se/sortiment/el-verktyg/elektronik/arduino/tillbehor/luxorparts-kopplingskablar-40-pack-hona-hona-p87906
I am using the Teensy 3.6 microcontroller with male headers. These are placed on a general purpose protoboard.
https://www.pjrc.com/store/teensy36.html
https://www.adafruit.com/product/590
I think the LVTTL is the best option forward. How do I access these pins from the program?
Best regards,
Ananya

2.png (1.04 MiB) Viewed 7572 times

This is the cable we normally use to connect the LVTTL.

According to the Schematics:

3.png (75.78 KiB) Viewed 7572 times

(JP3) It has 8 pins. TTLN, TTLP, TTL0, TTL1, TTL2, TTL3, VCC, GND.
As long as you don’t use pin 4 or pin 3 (GND and VCC respectively) you will be alright.

I show you which one is which one:

4.png (122.36 KiB) Viewed 7572 times

The pins of the FPGA:

Code: Select all

EMC2-DP V2        JBX       JBX PIN        JMX PIN      JMX             TE0715-30
CARRIER SIGNAL                                   FPGA PIN     SIGNAL
TTL3/U15-1/JP3-8     JB2           12            11              JM2          R3             B34_L17_P
TTL2/U15-4/JP3-6     JB2      14            13              JM2          R2             B34_L17_N
TTL1/U15-6/JP3-7     JB2      16            15              JM2          P3             B34_L18_P
TTL0/U15-3/JP3-5     JB2      18            17              JM2          P2             B34_L18_N
TTLN/U16-3/JP3-1     JB2      22            21              JM2          K4             B34_L11_P
TTLP/U16-1/JP3-2     JB2      24            23              JM2          K3             B34_L11_N


I don’t know if your cables fit in those pins. Did you check it?

Timoteo

Great information as usual Timo!
I think LVTTL will work.
I will use one of the pins to communicate with the microcontroller. I dont know if the wires I have fit. I will ask Asbjorn to check. He is the only one at NTNU with a board.
I will keep you posted.
- Ananya

[Ananya.Muddukrishna]

I got confirmation from Asbjorn that the TTL port pins match the GPIO cables I use. Also, he found that 1.8V is the only configuration that works. This means that I need to use a level shifter while talking to the microcontroller.