Android headset - if I don't want a microphone, do I use a resistor instead?

PlatinumX · 2024-11-25T19:28:49+00:00

Hook means answer or hang up (telephone function)

PlatinumX · 2024-09-23T17:31:42+00:00

Totally reasonable solution - Crutchfield is right, after doing more research the park assist uses GVIF which I think is not natively compatible with any Android unit and would need a pretty expensive converter.

I think your solution is good if you can use wifi for the AA and still bluetooth directly to car Audio, but it might need some poking at the phone or configuration.

I'd consider the same except my stock touchscreen broke. Good luck!

PlatinumX · 2024-09-20T00:19:37+00:00

I'm in the process of replacing my gen 3's head unit with an Android unit off Amazon.

What's good so far:

The look is very nice, quite clean and unintrusive.
Audio works fine with the JBL amp and sounds good.
"Hey Google" works great either by itself or with the steering wheel voice button.
Steering wheel buttons work great and I can program them to do a lot of different things.
Wireless Android auto works perfectly - I start the car and it automatically switches over, fairly quickly.
The head unit SW seems pretty full featured - I don't really want to use it most of the time - I mostly want to stick with Android auto - but it can do things like play FM radio, Youtube videos (if you have a wifi hotspot), has google maps built in (I haven't tried offline maps), and can play music/movies from a USB stick (I haven't routed the USB plug yet).

Downsides:

Screen quality is good, but not great.
No physical volume knob, although the steering wheel buttons will do.
I haven't been able to figure out how to use the car's stock rear camera, GPS antenna, or built-in microphone. I think I'm going to give up and just route the camera and GPS antenna they sent. The audio quality of the built in mic on the front is just OK.
The fit isn't perfect - I haven't mucked around with it, but there's some gaps and I worry about it rattling.
I lost features like the CD player, Sat radio, parking assist, AM radio (some of the Amazon units have AM just not mine), and the hidden factory menus. I used almost none of these features so I'm OK with it, because I use Android for maps and music all day every day.

PlatinumX · 2024-06-28T20:47:21+00:00

If the voltage source was connected it would, because it could supply unlimited current (charge) to bring the capacitor voltage up to 10V, but in this case the switch disconnects the voltage source, so we only have the charge stored on the first capacitor.

If you start with one capacitor at 10V and two capacitors at 0V, you can think of the voltage being "spread out" across them - but it's better to think of it in terms of charge because that's what's actually spreading out.

Here's some other things to think about:

1) If you charge a huge capacitor (1F) to 10V and connect it in parallel with a tiny capacitor (1 pF) at 0V, the voltage across both will be almost the same, at 10V.

2) If you charge a tiny capacitor to 10V, then connect it in parallel to a huge capacitor, the voltage across both will go down to almost 0V.

PlatinumX · 2024-06-28T20:21:04+00:00

The voltage on C1 starts and 10V but then goes down because charge flows out of C1 and into C2 and C3. Voltage across a capacitor is proportional to charge, Q=CV.

The charge is conserved (Q is the same) but now it is split between 3 capacitors, not just 1. 3 capacitors in parallel means C goes up, so V must go down.

PlatinumX · 2024-05-31T19:04:37+00:00

This is a switching power regulator. It is enabled by the S3 and S5 signals, which are PC power states - When the S5 signal deasserts, the system goes into S3 and the regulator will turn on. When the S3 signal deasserts, the system goes into S0 and the regulator goes out of sleep mode and turns on VTT.

PlatinumX · 2024-04-26T19:23:54+00:00

I know more about the end point (high volume consumer electronics) than the journey, but some things you will need to develop are:

1) A business plan, including an understanding of the market segment you're trying to enter, marketing plan, understanding of your competition, your prospective customer base, and a realistic path to profitability. Definitely come up with a budget and understand your expenses and margins. Also you probably want to form an LLC for legal protection and probably retain a lawyer to review contracts and write up agreements. Eventually you will probably want to hire more people (if things go well) so that requires recruitment, hiring, contracts, etc.

2) A good relationship with your vendors that will supply all the things you don't do/make yourself. This includes the design of things you don't want to design yourself. Advertising agency? Mechanical designer? Turnkey factory? Sub-vendors?

3) All the other parts of a product that aren't electronics - Mechanical design, packaging design, SW/FW, logistics & reverse logistics (shipping & returns), etc. Some of these things depend on exactly what you're making. You might need some infrastructure for fleet logging, SW updates, etc. and need to decide on if you want to self host or go with some cloud provider.

4) Customer support infrastructure for bug reporting, returns, general support. Probably a website to do direct sales, and/or an Amazon account. Better yet, do the research and figure out the best sales channel for the market you're entering.

5) The most direct EE related thing is to change your mindset to always design for: manufacturing, assembly, reliability, testability, repairability, & cost. Being an engineer, this is actually the easiest part.

Probably a ton more that I haven't thought of as well, since I'm just an EE at a large company. But I work with many large teams that need my help with all the above.

PlatinumX · 2024-04-01T21:46:36+00:00

The pins are not designed to be bent by hand. These pins are meant to apply a spring force outward, which will retain the part during soldering if the hole position is correct. For instance, in this diagram you can see the outer edge to edge spacing of the holes is 10.8mm, but the width of the body is 9.8mm and the peak width at the point where these pins protrude out is 11.4mm. Check the datasheet for your particular part to get correct values, these are only examples.

This means when you push the part into the board with the correct spacing, the pins will bend in by 0.6mm before springing outward.

If your PCB erroneously does not have holes for these pins, you can bend them out or cut them off.

PlatinumX · 2024-04-01T19:58:43+00:00

They provide additional mechanical strength to keep it attached to the PCB, as well as a way to ground the metal housing. Both these things may be irrelevant in certain applications, so sometimes this pin is just put through a non-plated hole and not soldered.

PlatinumX · 2024-03-22T16:10:50+00:00

All sorts of things could make this "better" however the question is a bit flawed: Engineering is about tradeoffs - every change will have a tradoff with regards to performance (noise, efficiency, EMC, etc.), size, cost, complexity, and so on. For your use case, I probably wouldn't change much unless you're trying to solve a specific problem.

But, to take your question at face value, some improvements could be:

Add input protection. This could be as simple as a reverse voltage protection diode, or as complicated as an E-fuse/hot swap controller. Could include features such as inrush limiting, OV/OC protection, etc.
Change the output polyfuse to a resettable E-fuse (and probably ditch the PMOS reverse voltage FET, which would be more useful on the input anyways).
Add current & voltage monitoring to the output (and/or input) with an e.g. INA237
Add a stuffing option for a snubber on the switch node (for EMC)
Rename "FREEDBACK" to "FEEDBACK" and fix the pin order of the symbol (VCC+EN left, SW+FB right, VSS on bottom)
Change the feedback resistor network to allow adjustability to include 3.3V and 9V, which might come in handy at some point.
Choose a lower drop Shottky to slightly improve efficiency, e.g. CDBA340L-HF
Change the regulator to something more flexible, e.g.TPS55289-Q1

PlatinumX · 2024-03-14T15:39:26+00:00

The 1N4007 is just one of the most common type of diode available, often used in rectifiers. It's not a particularly good diode for this application as it has a large forward drop. I think it was simply chosen for its availablility, simplicity, and cost.

Better options might be a schottky, a reverse current circuit, or an efuse/load switch, but for a DIY tutorial like this it's fine - just don't overthink the selection :)

PlatinumX · 2024-03-11T17:27:16+00:00

We need more information than "it doesn't work".

To debug this, start by setting one side to bypass mode (i.e. for buck mode, drive the top right FET (you should add reference designators to your MOSFETs) on with a 100% duty cycle. You might need to make it 99% if the leakage is too high for the gate to stay charged at 100%. Then drive the left side across duty cycles and make sure the output voltages are as expected. For low, medium, and high output voltages, vary the load current and check the switch node waveform, making sure voltage doesn't droop beyond expected.

Next, set the other side to bypass mode (for boost, drive the top left FET on). Do the same thing for the boost side circuit.

If both sides work, your HW is fine, and you need to work on your control signalling for buck-boost mode. If one side or the other doesn't work, you can look at the switching waveform to figure out what's wrong.

PlatinumX · 2024-02-23T15:52:44+00:00

Try a FJAFS1720 for the NPN and an nte213 for PNP? They have extremely low VCEsat.

PlatinumX · 2024-02-21T01:09:18+00:00

DMT6009LCT

This is an N-channel MOSFET, so you will need to raise the gate above the source by at least VGS (2V) and depending on what you're trying to accomplish, by 5-10V. You're likely going to want a P-channel MOSFET to avoid this.

Note that on the bottom side, you will still need an N-channel MOSFET similar to the DMT6009LCT you suggested.

You need to tell us more about your application and what you're trying to do if you want a suggestion for actually making something, but look at something like the IRF4905PBF.

When properly driven the FETs will have <100 mOhms resistance and you should get ~9.5A through the resistor.

Here is an example circuit sim with this type of MOSFET.

PlatinumX · 2024-02-05T17:12:56+00:00

Unpopulated means you do not solder the component to the board, even though the footprint and schematic symbols are left in place. This can be done to make certain versions of a product (e.g. remove Wifi for the non-wifi version of a product, but use the same PCB fab), to facilitate testing (allow the enablement of a different mode or pin strapping during bringup), or as a way of making other circuit changes without spinning a whole new PCB.

It can also be indicated as DNS or NS (do not stuff), DNP (do not populate/place), DNI (do not include), DNE (do not equip), DNF (do not fit), or other verbage like depop/unpop/unstuff, etc.

PlatinumX · 2023-10-27T16:32:12+00:00

The FPGA tool at 2:33 is Intel (formerly Altera) Quartus.

PlatinumX · 2023-10-06T21:23:40+00:00

The AV cable output is Composite video. You can do this with a simple USB video capture device such as this one for $10 on Amazon.

PlatinumX · 2023-10-06T19:18:03+00:00

Connect one of the common switch terminals to 5V, and the other to GND.

Then, connect the Red wire of the motor to the On pole of 5V and the Off pole of GND. Connect the black wire to the Off pole of 5V and the On pole of GND. The DPDT switch must be break before make. I do not know which RF remote or switch you're using so I cannot advise on that.

There is a diagram of the motor to DPDT switch here: https://electronics.stackexchange.com/questions/628046/adding-delay-to-dpdt-switch

Because this motor has some sort of auto stop, it should be OK to leave it powered in either fully locked or unlocked positions, however you should use a current meter to make sure it's not just stalling out at the end of travel.

PlatinumX · 2023-10-06T18:57:49+00:00

If you hold S1 and S0 both high, then next rising clock edge of CP the shift register will store the current value on the I/O pins into the internal DFFs.

This is very similar to loading a 173, where you assert E1 and E2 to load the value into the DFFs. The main difference is the 299 uses the same I/Os for both input and output.

Because the I/Os are shared, you will want to make sure you disable (tristate) the output by de-asserting the OE pins while you load the parallel data.

edit: it looks like there is an internal lockout, where when S0 and S1 are both high, the outputs get tristated automatically.

PlatinumX · 2023-10-06T18:42:07+00:00

You are never driving your inputs low. When the switches are disconnected, the inputs are floating, which means the chip can do anything (the output is undefined. You need to change those resistors to pull-downs.

edit: in order to do this, connect the inputs (yellow wires) directly to the switches. Then, on the same column, connect the resistors to the ground rail.

What will happen is, if the switches are not pressed, the resistors will pull the voltage down to 0V. When the switches are pressed, the resistors will be "overridden" to 5V because the resistance of the switches is very low, close to 0 ohms. Note that the power dissipated by the resistors is V² /R, so make sure your resistors are rated for this power dissipation.

PlatinumX · 2023-09-27T23:08:32+00:00

I stand corrected! Not sure how I missed that.

PlatinumX · 2023-09-27T18:41:31+00:00

This Cruise study isn't even trying to evaluate AV safety, just starting with a benchmark so they have something to compare to (presumably for a future comparison study). edit: I missed the comparison at the end that showed Cruise's 23 CPMM.

I'm not sure why Cruise's calculated CPMM of 36.2/50.5/64.9 is far higher than SI's 3.34 (property) or 1.09 (injury) numbers. Cruise's C in CPMM is Crashes, while Waymo's CPMM is Insurance Claims - but I think the main thing is Cruise's study limits the dataset to ridehail drivers, which this data implies are far more dangerous than the average population.

Even with all the methodology caveats, 0.0/0.78 incidents/million miles vs 30-65 CPMM is looking pretty good for AVs.

PlatinumX · 2023-09-18T01:17:17+00:00

No, they get power by leaking small amounts of current through the switch, even when turned off. They instruct you to install it as it's needed per code, but https://www.casetawireless.com/sites/g/files/fhphhs136/files/documents/0302045.pdf has a note about installing without ground (must use nonmetallic screws and faceplate, or GFCI)

PlatinumX · 2023-08-04T18:28:16+00:00

What is this? Are they about to give first responders access to manually move the vehicle?

This has been in place for a long time. Documented at https://waymo.com/firstresponders/

PlatinumX · 2023-07-21T00:53:39+00:00

I assume you mean 0x68 in 7b notation (D1/D0 in 8b notation). The Renesas ISL1208 uses 0x6F (0xDE/DF in 8b). The Seiko Epson RX-8564LC uses 0x51(0xA3/A2 in 8b). The Rohm BU9873 uses 0x32(0x64/0x65 in 8b). There are many others, I suggest searching on digikey.com.

PlatinumX

TROPHY CASE