Could anyboy tell me that MAX232 is same as 74HC14?

[Truman]

Could anyboy tell me that MAX232 is same as 74HC14? I saw a flash cable with parrall port use MAX232 , so i think it should same as 74HC14 . is it ?

Anyone can tell someting detail about this will be appreciated .

[weremanok]

hi truman,

the max232 is a chip that converts rs232 logic signals to TTL logic signals. the voltages for rs232 is: 12 volts represent a logic "0" while -12 volts represent a logic "1". the voltages for TTL is: 0 volts for logic "0" while 5 volts for logic "1". so if you input 12 volts to the max232, the output would be 0 volts, and if you input -12 volts to the max232, the output would be 5 volts. the 74hc14 chip is a schmitt inverter. it accepts TTL logic inputs and it inverts it at the output. if you input logic "0", the chip will output logic "1" and vice versa. the parallel port outputs TTL logic signals so i don't think that the max232 chip will work with the parallel port. i am guessing that you just saw a rs232 port with 25 pins because rs232 comes in 9 pin and 25 pin configurations.

i hope my explanation does not confuse you in any way.

[Truman]

As you say i can understand . but this adapt i get from one of my freind . And he has used this adapt and additional cable to Flash nokia phone . So , now i am a little confusion , as what you said , then is there some Flash cable can use RS232 port ? ( i always think that flash cable only has parallel port format )

[weremanok]

hi again,

at the back of the pc, the parallel port is a female connector while the serial port (rs232 port) is a male connector. Check if the cable is a male or a female connector. flashing nokia phones involves using the parallel port while updating faid, uploading logos, ringtones etc. involves the rs232 port. hope this helps.

[Truman]

thank you first .

i know this well . But it is a male adapt , absolutely connect to parallel port . ( but inside the adapt , it has a MAX232 IC ,hehe) So this is the reason why I ask the question .

Maybe some special software can use these type flash cable ?

(well , anyway , i will check the software which my freind use , because now i only got the adapt but no software ,)

[weremanok]

can you attach the schematic so that i can take a look at it? i'm curious on how your friend used the max232. thanks.

[Truman]

ok . I was curious too.

To make the detail schematic maybe difficult , and now I dont have a DC camera to photo it for you . So , I just try to explain it as clear as possible.

It has 6 output lines , color is 1.black 2 white 3 green 4 brown 5 yellow 6 red , and from these , through a RJ45 socket , you can connect to different type phone adapt , each line ( 1 - 6) connect to " 1 Vpp 2 Fbt 3 Mb 4 Fbr 5 Gnd 6 Btemp " .

And it use pararelle port , the schematic is almost same as that FLASH cable which use 74HC14 . That is why I ask from the very beginning " is MAX232 the same thing as 74HC14"

another question, can you give me some infomation about 74HC04

[weremanok]

do you know what is connected to the pins of the max232?

the 74hc04 chip is a hex inverter. it is similar to the 74hc14 except that the 74hc14 is a schmitt triggered inverter. the 74hc04 is just a simple inverter, input logic "0" and it outputs logic "1" and vice versa. for the 74hc14 the output does not entirely depend on the input. it has something to do with the voltage input level to the chip. TTL logic has a voltage range. let me explain it this way: you can input a logic "0" to the 74hc14 but because of the voltage you inputted, the output might not be a logic "1" and vice versa. so the difference between the two is their switching characteristics. it's hard to explain what a schmitt trigger is without drawing diagrams. i hope i explained it clear enough.

[Truman]

Thank you very much .

I have learned this in school , but I almost forget it at all . It seems that in this adapt , there maybe some special use or some wrong information i got . So , Let it be . If i have some further information , i will let you know .

[weremanok]

ok. just keep me posted. just wanna see the schematic because i'm really curious about it.

[Truman]

I checked it . It was same as that another flash cable use 74HC14 . And , my freind told me , he hasn't use this adapt but it comes from the saler together , and should work ok . But I tried , failed . Maybe it is just a wrong thing ? Sigh ~

[Glen Borja]

maybe there are two attachment for that cable, I am trying to assemble a cable which can be interchanged with flasher and an mbus by just using more wire in the cable and using a db9 connector the same as the flasher connector. Maybe this is why.

[Truman]

yes£¬i think so

and use latest ver ¡°nmp DCT3 Flasher 5.14¡± and a special parallel port £¬ maybe it's possible to do this ¡£