Postbag: #26 - 74HC595 PCB, 30V LCD Meter, Qi & USB Charger

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At 00:50 you said: "So, one of the things you can't do on an Arduino, is write an 8-bit byte of data to an 8-bit port. You can't write, in one go, a byte to an output". Well, indeed you can. With PORTA, PORTB, PORTC, PORTD etc. PORTD = 0xff will set pin 0-7 high provided they are set to output. I love you videos by the way, just feel like nitpicking at the moment. :)

jeffmerlin

This may have already been said, but port 2 of the charger does have the 4 resistors for apple data voltage levels, just 2 of them have been moved slightly because of an unpopulated SOT23-5 pad.

KX

I had a Fuller speech unit for my ZX Spectrum that used the SPO256 chip. Then I bought a chip from Tandy and made my own speech synthesiser for my Sinclair QL. I always wondered about the AL2 bit at the end. I guess it means allophone set 2. But what did allophone set 1 sound like?
If you want a modern alternative then check out the speakjet chip.

bigclivedotcom

Do not fully agree with the statement on 1:06 about writing 8b in parallel. For instance, you could use PORTB=B101000; to set digital pins 7, 5, 3 HIGH and pins 6, 4, 2, 1, 0 LOW in one go. The example is straight from arduino's PortManipulation reference page.

Yes you can set bytes to ports on arduino! They use Atmegas, so you can use direct port manipulation!

Leonelf

The Currah microspeech for the ZX Spectrum uses the spo256 speech chip.

pcuser

I believe that is the chip I had from Radio Shack. I built it into my Atari 400, driven by the joystick ports. Used it for years with a cassette tape recorder and a modified modem to take phone messages or switch to the modem for the BBS I ran. A caller would be told to hold for 30 seconds, then a carrier was sent while the 400 monitored CD, if that timed out it would ask the caller to leave a message and roll the cassette. Over three decades ago but may still be my most complex project/program.

HillOrStream

Shortly after Apple released the iPad, USB specs were revised to add the ability to up charge current from 1A to 2A. Only problem is that they couldn't enable it for every device, or else they could seriously mame older devices. So these "smart" chargers actually use some of the data lines on the usb cable to talk to the device and essentially ask it if it can handle the 2A charge. It it responds yes, the charge device goes into quick charge mode. If it responds no (or more often, sends back no response at all) the charge current remains limited at 1A.

thejo

Your Videos are always great thanks!! Maybe put the new LCD in a ZIP lock and seal it up except the corner ... they have worked very well for me in the past as a temporary solution. :)

healthman

Port 2 on the USB charger has the same resistor matrix, but the other two are below and to the right, aren't they?

velocityphotography

For the bike battery, do get a BMS like the one you mentioned.

I would suggest you get a fixed function charger too, even the BMS will allow you to get away with accidentally using the NiCD charge program on lithium batterys. The RC chargers are neat, but not exactly something I would build into/use as part of other things.

Fixed charger and BMS and you should be rather safe. Do NOT skip the BMS.
There are details for the packing too, but I rather not advice on how to stop a flaming battery. Don't go super-cheap on those parts.

As for IO pins, a AVR microcontroller and a breakout board should give you lot of paralell IO.

One of those 64/100 pin TQFP SMD packages would give you LOTS of 8 bit ports.
(and ports in general)

As for me, xmega and avr dragon looks tempting. I have looked at the xmega datasheet, and it lists features like DMA and internal routing network.

erlendse

We put a couple of similar LCD voltmeters in one of our trailers.

douro

hi, about that usb car charger: smaprt ports are supposed to adjust the voltages in usb data lines to find out maximum current draw for the connected o/p device. cause some high end fones put these tricks in their usb charging systems.

iceberg

13:56 the 2 5-pins ic are just like DCP. TI has TPS2511 to fulfill same purpose

fatpo

seems like all 3 universal usbs from the ec technology charger have the same resistor network the one on the second port is only slightly different alignment, but the resistor codes are the same.

DantalionNl