feeling a little stupid tonight, but a few questions about this UART circut... Firstly, on the MAX232 chip... does it mean that the input data goes to pin 13, then it runs through a diode to pin 12? or are they intergrated on the chip? Second question: On the 74HC6040 chip, pins 4,5,6 are drawn connected to nothing but a dot... its really not connected to anything? why do they draw it if it really isnt connected? Last Question: About the pot, with the knob facing towards you, which pins go to which part of the lcd? Thanks for your help guys.
Q1: Unless the part is inside the chip box (the drawn box) then it's external (so, in that instance, it is internal) Q2: The dots are simply NC (no connects). They show you in case you want to connect them to something else. It shows that they're not used by the system, so you're more than welcome to Q3: Pots are reversible. The arrow pointing to the middle is the center pin, then the other two don't matter (as long as they're connected)
Question 1: Pin 13 runs to pin 12, that symbol they run through is a logic symbol - looks like it acts also as an inverter; it is intergrated onto the chip. Question 2: Sometimes those are drawn and depending on the design of the chip you may have to ground them or attach to V+ since they are described as being in a "floating" state. The reason you may have to attach them is because those pins may pick up stray signals. Just found out: Pin 13: Parity Error Pin 14: Framing Error Pin 15: Overun Error These are all on low until an error occurs which sets one of the pins on high. I guess you can either leave them be or attach each pin to an LED to have error control indication. Question 3: The middle pin on the pot goes to pin 3 on the LCD; the other two are arbitrary.
oh yeah, I forgot to mention those internal parts are inverters, not diodes... inverters have a bubble where diodes have a line
yeah thats an invertor on that circuit not a diode. use an 74LS04 or equivalent, pin 1 to pin 19 on the CDP, pin 2 to pin 6 on display (and pin 18 on CDP), pin 14 to +5V and pin 7 to 0V.
And there you have it. I'm sure there are plenty of inverter chips out there, and in case you didn't know, the BEST way to get chips for small projects like this... ...is to steal them? The sample system is for genuine professional developers, not for freeloaders to save a few cents on common components. As with any other piracy discussion, rest of post deleted. http://forums.bit-tech.net/showthread.php?t=32917 for a full & frank discussion.
If I remember correctly, the MAX232 chip actually contains a small voltage doubler and inverter. The PIC, along with most other microcontrollers, uses logic levels of 5V and 0V for '1' and '0' respectivley. Whilst some PC serial ports accept this, RS232 actually states that the voltages for PC serial conections should be +12V and -12V. The MAX232 runs on 5V, like the PIC / other microcontroller, but converts the signals so that they are definitley compatible. (i.e. boosts the voltage from the microcontroller going to the PC RS232 port, and reduces the voltage coming from the RS232 port to the microcontroller) The MAX232 uses a couple of the capacitors connected to it in it's own charge pump circuits.
i agree, not right to steal or "sample" things... do you go to price club to have lunch? walk around the store eating all their samples? BTW, i picked up the chip at the store i always go to, little place downtown, very reliable, its a pleasure to buy from them. I rather pay the money to shop at their store than to wait around for some low grade sample crap.
Sampling is a fantastic way for getting components that are rare/hard to get, most companies will sell these at cost/give away at a loss to help you with designs. If your not making a new design, you shouldn't sample, you will be hurting everyone who makes new products on the cheap (ie, students like me).
Whoa there Mr. High-horse... I am a student and all my designs are prototypes which is well within the "sample" criteria. Our profs TELL us to get samples to design our stuff. If I were to make something for mass production and/or to make money off of, it would be a different story. Also, those places only let you have a certain number of samples. Once you surpass that number, you have to buy the stuff from then on. I think you're being a little too "holier than thou." This is a civil discussion and i was merely pointing out that if he is making a single version of WHATEVER he's making, for the smaller chips he can have them overnighted for free from TI or National Semiconductors
err question: What software should i use for my LCD? (hd44760 connected through uart to serial) Examples please
Basically you can send any valid HD44780 command out the RS-232 port RS is controlled by DTR, and you can only use write commands, because R/W is tied. For more about the RS-232 port and how to code for it, see the same site as the one for that schematic.
All hobbyists make single versions 99% of the time - are you suggesting every hobbyist should scam their parts? If it's part of a school activity, explain honestly to the firm and and ask for their help, many will. Read the link I posted for comments from several other people whose opinions I respect.
The fact of the matter is, you modified my post b/c my opinion differs from yours, and that's juvenile. I can give you many reasons why they set up the sample program for people like me (and you, and lots of people), but this isn't the thread for it. It's just sad that you did that... you could have posted below me and stated your opinion, but instead you use your "mod" prowess to take out parts you disagree with. It doesn't matter if you're twice my age or half it, that isn't the "adult solution."
The fact is, I see such posts as no different to ones promoting software piracy or any other form of theft. Any I see will be deleted or edited as appropriate. Don't expect me to condone dishonesty, and it's nothing to do with age, it's upbringing.
