This is a new NRF24 module, works perfectly, this is from the manual, note Pin 1 has a square of solder rather than a circle.



The pins are on the underside of the board, right hand image.

So having been working with these for months using individual strands of colored Dupont wires, I was pleased to stumble upon these on Amazon:



Obviously that IDC connector can be attached to the board two ways, so I grabbed a multimeter and identified which hole maps to which color - then the insanity hit me.

In that picture, the "bottom right" hole maps to brown, the hole to the left of that maps to orange...

With that wiring, the plug would either see brown connected to Pin 7 on the NRF24 or to Pin 2 on the NRF24. If the pins stuck up on the other side of the board it would match fine.

The colors of the wires do not correspond to the pin numbers shown on the board - insane.

Of course the device can be wired OK but these mismatches can be source of immense confusion - for me anway.

If the colors matched the pin numbers it would be easy to use:



Brown would be GND, Red would be VCC, Orange would be CE and so on, but its a mirror image and I need a straitjacket.

In reality

Brown => VCC
Red => GND
Orange => CSN
Yellow => CE
Green => MOSI
Blue => SCK
Purple => IRQ
Grey => MISO

 

The picture (of a similar module if not the exact one) shows the silk screen of the connector on the TOP of the board. If the connector is installed on the bottom of the board, the even and odd pins are reversed.

It's a design screwup.

 

The picture (of a similar module if not the exact one) shows the silk screen of the connector on the TOP of the board. If the connector is installed on the bottom of the board, the even and odd pins are reversed.

It's a design screwup.

If I stand upside down and in front of a mirror with this, everything's fine...

 

If I stand upside down and in front of a mirror with this, everything's fine...

Designed in Australia, mate.

 

Designed in Australia, mate.

 

Designed in Australia, mate.

 

Connect 2 x 4 header to another 2 x 4 header and ignore the colors.

 

Connect 2 x 4 header to another 2 x 4 header and ignore the colors.

I just made sure the NRF pins go to the correct Nucleo pins and they do now, work fine, colors are secondary but earlier I was going to rely on them as I planned to swap them.

All working now anyway and while testing I established the nature of the fault in those problem NRF24L01+ devices.

Turns out they listen for and receive acks but they do not generate them, so when running as a receiver they receive but never send an ack.

If I transmit with an old one and receive with the newer modules the transmitter gets the acks fine.

I wanted to be able to connect and disconnect these more easily, the eight individual strands made that very confusing and fiddly, now I can just connect disconnect without thinking (almost).

 

Would you gurus here agree, that the IDC female connector is wired correctly, that's how they are and should always be wired (if standard pin numbers are to match color code) ?

If we look downwards onto the pins of the male connector/pins then Pin 1 should be top-right? i.e. if the module had had the pins coming toward the viewer in the left hand image, it would have been correct.

 

It depends on which pin the first cable connects, it could be on the left or on the right.
You always have to check to be certain.

I have plain grey 3M cables with a red tracer on one edge. Quite often it is not on pin-1 when connected to a IDC connector.

The other observation is that they do not number IDC connector pins the same way they number DIL IC packages.

 

The colors of the wires do not correspond to the pin numbers shown on the board

According to which standard?

 

According to which standard?

Well if I have an IDC female connector attached to colored 8 pin ribbon cable, would it not be sensible for PCBs to expose 8 pin male connectors, in such a way that IDC Pin 1 mapped to Brown in the ribbon cable and Pin 2 mapped to Red in the ribbon cable.

I know there's no formal standard, but would you expect a female IDC plug ribbon cable colors to match these male pins (looking down onto the upward pointing pins)



or these male pins (looking down onto the upward pointing pins)


If the IDC female connector had holes on its top and bottom surface, this question and problem would evaporate.

I guess the real fix here is to buy my own IDC colored ribbon cable and empty IDC 8 pin connectors and just make them so as to match the actuality of the board Im dealing with.

 

According to which standard?

Exactly, there is no standard for pins or colors.

 

Well if I have an IDC female connector attached to colored 8 pin ribbon cable, would it not be sensible for PCBs to expose 8 pin male connectors, in such a way that IDC Pin 1 mapped to Brown in the ribbon cable and Pin 2 mapped to Red in the ribbon cable.

I know there's no formal standard, but would you expect a female IDC plug ribbon cable colors to match these male pins (looking down onto the upward pointing pins)

View attachment 348989

or these male pins (looking down onto the upward pointing pins)
View attachment 348990

I never assume or expect anything logical with these types of modules that have no standards for anything, connections wise. As we well know, some of then don't every comply to the operational datasheet standards for X type of device. Colors to match? Welcome to the world of cheap hardware.

 

https://www.amazon.com/Antrader-2-5...x=idc+female+header+8-pin,aps,225&sr=8-1&th=1

https://www.amazon.com/uxcell-Rainb...22&sprefix=8+idc+ribbon+cable,aps,1213&sr=8-8

 

I never assume or expect anything logical with these types of modules that have no standards for anything, connections wise. As we well know, some of then don't every comply to the operational datasheet standards for X type of device. Colors to match? Welcome to the world of cheap hardware.

Fair point, here's me whining about colors not matching, when last week the RF chips I was using didn't even generate ACKs as they should !

What killed me though was the way

Pin 1 => RED (2)
Pin 2 => BROWN (1)
Pin 3 => YELLOW (4)
Pin 4 => ORANGE (3)
Pin 5 => BLUE (6)
Pin 6 => GREEN (5)
Pin 7 => GREY (8)
Pin 8 => PURPLE (7)

By the way, anyone wanting to express Brown on this forum, use: #895129 and not the default here: #A38F84

Anyway, I will buy some 8 pin female connectors and 8 pin colored ribbon cable, its easy to make it the opposite way that maps to these devices.

There's a very old saying in computer programming: IF IT CAN GO WRONG IT WILL.

The more we allow, tolerate small issues to accumulate, the greater the risk of some kind of non-minor failure.

 

...
There's a very old saying in computer programming: IF IT CAN GO WRONG IT WILL.

The more we allow, tolerate small issues to accumulate, the greater the risk of some kind of non-minor failure.