Repairs - Mazda 5 Aux input

 

This time I spent some resources to fix the AUX input on my Mazda 5 2012.

SmartPhone audio accessory

Some notes about some audio accessories for smartphone.

Hype Retro Walkie Talkie handset

This funny toy is shaped like a traditional-style ham radio microphone.

The idea is to "transform" the smartphone into an Ham radio. For example, used with Zello can facilitate to use it in a mobile environment or for who is nostalgic about it.

I tested it on the Samsung tablet but is not working with Zello.
However is working with other applications. This suggests that there are other differences other the 3.5 mm jack pinout.

Let's open it up

The quality of the gadget is of course very low. Beside, for 5$ really is not expected to be better.

The gadget

To open it there are just four Philips screws

The little board has a small amplifier based probably on  a LM386.

There are two push button and a trimmer for the ON/OFF and volume setting.

The small push button on the top is the one that is used to start the conversation.

The big push button on the side simply mute the speaker (IMHO wrong  choice since normally the PTT button is on the side on a normal/standard mike).

Operations

The idea is to plug the mike in the smartphone audio jack and turn it on.
After that the audio output is redirected to the small speaker and when pressing the PTT button, the mike is activated.

Smartphone audio cable adapter

Unfortunately doesn't seems in the smartphone and tablet world, to exist a single standard for the audio connectors (see article about the smartphone audio jack).

On the market do exists cable converter of any kind, however they are often unnecessarily costly.

If you need an audio jack adapter between the main two standard in the smartphone world, OMTP and CTIA, here what I did.

Shopping list

Quite easy ... we need three things :

• a 4 wire cable
• a TRRS male jack
• a TRRS female jack

I solved buying the needed material from Sparkfun.

I ordered a TRRS male jack with 18" of cable (CAB-11580) for $1.95 and a TRRS jack breakout (BOB-11570) for $3.95.

The TRRS jack breakout

It is possible maybe to find just a TRRS female for less, but the breakout is more flexible since it can be used also to provide a test platform (hook up oscilloscope, ecc.).

For about 9$ (the material plus shipment) is possible to have all the necessary to build the adapter.

A ready made cable converter can be found usually around 11$ plus shipment, but  the advantage to build it is that can be modified for other type of connections.

Schematic

OMAP<--->CTIA

Well, is really quite straightforward.

It is simply matter to connect the Tip and first Ring directly, and then swap  the other two.
The TRRS jack with the cable has this pinout :

• Tip - red wire
• Ring - white wire
• Ring - green wire
• Sleeve - black wire

On the PCB are marked the positions, so it is straightforward to connect the wires.

Smartphone/tablets audio connectors

One of the few things really annoying is when manufactures decide to don't follow a single standard for the connectors of their products.
I have around some smartphones and there are differences on the audio (3.5 mm) connector.
These differences creates problems with some accessories.

For example I bought a very nice desktop phone stand from Aptiva, but I soon discovered that it is incompatible with my Sony Ericsson Xperia.
The same for a Hype Retro Walkie Talkie handset I wanted to use to enhance the Zello experience.
On the Sony is not working at all, on the Samsung tablet works in part (see the note on the bottom of this article).

So there are differences about the connection of the 3.5 mm audio port on these devices.
This article is trying to document the pinout of different phones/tablet and giving information about this problem and how to solve it.

Introduction

The typical 3.5 mm jack is divided in different areas :

• Sleeve
  The part of the connector close to the handler, the cover.
• Ring
  The part of the connector separated by a insulator ring
• Tip
  The far part of the connector, the "point"

There are many different types of jack.

In the figure below, there is an explanation of the main parts of such connector.

This type of  jack is called TRRS  (Tip/Ring/Ring/Sleeve) and it become the "standard" for smartphones.

The most known type of jack is the one used to connect the standard stereo headset.

This type of jack is called TRS, from the initials of the connections :
Tip - Ring - Sleeve

CTIA Audio jack

CTIA defined an audio connector.
It is a TRRS  :

• (sleeve) Microphone input
• (ring) Ground (common)
• (ring) Right Audio out
• (tip) Left Audio out

iPhone 4S

Many audio accessories are labeled as iPhone compatible.
This means that the majority of the audio accessories found on the market follow the Apple standard for the 3.5 mm audio connector.
The iPhone/iPad audio jack follows the specifications defined by CTIA.

So every accessories that declare to be iPhone compatible has the pinout shown above.

OMTP audio jack

Android, as general rule, seems follow a standard defined by a group called OMTP.

However different manufacturers choose to follow the CTIA, others didn't.

The main difference between the CTIA and  OMTP is switching the place from Ground and the Mic.

So each Android smartPhone or Android  tablet can have different audio jack pinouts. That's very very bad.

This is the OMTP connector :

So let see different brands what offers.

Keep in mind that usually models of the same brand uses the same pinout, but it could be different !

So never assume.

Sony Ericsson Xperia LT18a

OMTP standard

In order to use Apple iPhone standard accessories, is necessary to use a converter.
It is possible to search for CTIA<--->OMTP conversion cable or it is relatively easy to build one.

Samsung Galaxy Tablet 7" GT-3113

CTIA standard

Samsung SPH-M910

CTIA standard

FriendlyArm Tiny210 SDK

This OEM board can run Android 4.0.3.
It has a TRS jack for the audio output and a TS jack for the audio input.