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Hi,
I used VLSI 1011 chips before, they are a bit hard to get starting, but once you got it it's pretty straight forward.
Are you developing board or using proven design board and developing codes?
There is no major INT command, you read the MP3 hex and shift it to VLSI, it can take only...
Hi,
If your modem works with HyperTemrinal and not with your MCU, please check all the other Rs-232 signal, the RTS, DTS and two more.
Sim300 will not reply if this signal not handle correctly, this is called Rs-232 Hand Shaking, if the SIM board as MAX232 chip and all line connected, the it...
Re: Switches difference.
HI,
74HC595 is SIPO, what you mean "turn-on", if you wanted to connect your MCU I/O pint to 74HC595 , and extend the serial output of your MCU to parallel (8-bit), then connect them directly, no need for any switch, remember, MCU has good SINK type NPN connected to I/O...
Re: Switches difference.
Hi,
Well, I will explain in my designs;
When to use a transistor as a switch?
if MCU need to switch a LED on-OFF, or activate Relay, or buzzer or ...., I use NPN transistor, because, I do not worry about ground difference and no issue on huge current flow and...
Re: Switches difference.
Hi,
All the answer is referring to SWITCH operation ONLY, transistor and Mosfet can operate other means too.
Transistor Base current will go to Emitter (NPN) when used as switch, in Mosfet Gate current will not flow into Drain. In Opto-isolator, you will drive the...
Hi,
If the modem respond when connected to PC and not when connecting to MCU, then check out the following;
Only valid if connection via PC is using all the Rs-232 signals.
When the other Rs-232 is not handle correctly, modem will not reply to MCU which is connected with Rx/Tx only...
Hi,
If you have Windows OS, you can use HyperTerminal or any other Serial Terminal Program to send command to GM862 via Serial Port. (you should use this method to ensure your modem, power, sim card and serial cable is OKAY)
I have no idea about UBuntu, you should search UBuntu forum for...
Hi, Guys,
Just noted the whole issue with SIM900, is the problem solved, I am reading thru the 24 post, alot of work done.
We been using SIM900D for the past 24-month, our recent order of 200-unit, Feb-2012 order was tool problem, it looks like SIMCOM changed the hardware and had firmware...
Hi,
Honestly, using MCU will solve this problem easily, also the time and accuracy will be improved and you still can work on 2mA power requirement. Using non-MCU design will create few hidden issue, but accuracy will be low.
I am not saying one can not do with non-MCU, but component count...
Hi,
From what I noted in your post, you wanted to power 5V circuit from 56VDC source, that mean you need to drop 51V, I did not see any output current rating, so I assume it's 1000mA, I will give three design I do not know if you can source this components locally for design (1) but design (2)...
Hi,
Alot of choice, you need to navigate to National Semiconductor website, and use the online design tools, enter you working parameter for design (i.e component) suggestion, then look at sourcing and select suitable design.
M.Pathma
Hi,
I need to double check the datasheet, but from memory, the LM317, maximum Vin is about 36VDC, you might be over-driving the chip. I think you are trying to use the 220R/5W to drop the Vin to save value, but this is not the right method. also the LM317 need to drop 36V to 5V, giving 31V...
Hi,
For our Portable Fingerprint Verification product we used ready-made modules.
I found 3-major module supplier, ZK Software (China, low cost, have its limitation), Suprema (Korea, quite good, end-up using this), SecuGen (USA, very good, like it very much, but cost factor does not...
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