8-bit MicrocontrollersのトピックRe: When the I / O output switch input , I have encountered...

When the I / O output switch input , I have encountered...

xiaolin_gao — Sat, 27 Dec 2008 22:54:34 GMT

When the I / O output switch input , I have encountered a problem: the switch appear the 2.5V level, how to solve it? Thanks

Re: When the I / O output switch input , I have encountered...

JulsPower — Sat, 27 Dec 2008 23:57:14 GMT

do you have a pull up to 3.3V?

Re: When the I / O output switch input , I have encountered...

xiaolin_gao — Sun, 28 Dec 2008 13:50:42 GMT

Hello! could you point you in detail? close pull up still the same situation

Re: When the I / O output switch input , I have encountered...

xiaolin_gao — Mon, 29 Dec 2008 23:51:05 GMT

freescale engineers Where ah? Please help , thank you!

Re: When the I / O output switch input , I have encountered...

peg — Tue, 30 Dec 2008 05:03:43 GMT

Hi xiaolin,

I imagine most people are on holiday at the moment.
Also, if you provide some more details people may be more willing to help you.
The waveform looks quite strange, but is switching to the different levels quite positively.

1. In your question you mention input and output but don't say whether you are talking about something driving a MCU input or an MCU output driving something.

2. In either case, tell us what "something" is. (i.e. what is connected to the i/o you are measuring?)

3. Have you disconnected the i/o to be sure the distortion is being caused by the MPU side and not the thing that is connected?

Please answer the above questions and we may be able to start to get somewhere.

Re: When the I / O output switch input , I have encountered...

xiaolin_gao — Tue, 30 Dec 2008 21:34:52 GMT

hi.peg, I use mc9s08 to drive 122*32 LCD,The following program

#define A0 PTAD_PTAD0   /*_command or data*/
#define CS1 PTAD_PTAD1
#define CS2 PTAD_PTAD2
#define _WR PTAD_PTAD3
#define lcd_data PTBD
#define ENABLE PTCD_PTCD0

#define set_CS1() (CS1=1)
#define set_CS2() (CS2=1)
#define set_A0() (A0=1)
#define set_WR() (_WR=1)
#define set_ENABLE() (ENABLE=1)

#define clr_CS1() (CS1=0)
#define clr_CS2() (CS2=0)
#define clr_A0() (A0=0)
#define clr_WR() (_WR=0)
#define clr_ENABLE() (ENABLE=0)

void wait_ready(void)
{
     //setReg8(PTBPE, 0x00);
    setReg8(PTBDD, 0x00);

do{
     clr_ENABLE();
     clr_A0();
     set_WR();
     NOP();
     }while(lcd_data & status_busy); //mask it dubug
   setReg8(PTBDD, 0xFF);

}

i use 68-type microcontroller connect to LCD,thank you!

Re: When the I / O output switch input , I have encountered...

kef — Tue, 30 Dec 2008 22:48:44 GMT

I guess you are driving two SED1520 LCD controllers or something like that?

Still it's not clear what you meant in your first message. But if you say you are using 68-type bus mode, then I don't see where you are pulsing E signals (CS1 and CS2 probably). If you select LCD controllers outside the wait_ready routine, then you should not set bus direction to output setReg8(PTBDD, 0xFF); before E signal is set back to 0.

Re: When the I / O output switch input , I have encountered...

xiaolin_gao — Tue, 06 Jan 2009 23:56:28 GMT

hi, kef

When I / O port pins appear 2.5V, I removed the external level, the external level measurement is 5V, and this I / O port pin level is 0V, and why?

When PTBSC=0x00, then level from 2.5v to about 0.8v, why?

thank you !

Re: When the I / O output switch input , I have encountered...

xiaolin_gao — Wed, 07 Jan 2009 00:02:55 GMT

Sorry! Wrong.it should be changed to

When PTBDS=0x00, then level from 2.5v to about 0.8v, why?

thank you !

Re: When the I / O output switch input , I have encountered...

kef — Wed, 07 Jan 2009 02:01:21 GMT

I guess it's because LCD controller drives the data bus. In 68 mode, to read from LCD you should:

1) make sure MCU data bus port direction (portB?) is set to input

2) set up address pins (A0)

3) set R/W pin to 1

4) set E pin (you call it CS probably) of one of LCD controllers (not both at the same time) to one

5) perform read from data bus port

6) set E pin(s) back to 0

I see steps 4 and 6 are missing in your code

Re: When the I / O output switch input , I have encountered...

xiaolin_gao — Sat, 10 Jan 2009 23:31:18 GMT

hi,kef

void wait_ready(void)
{
     //setReg8(PTBPE, 0x00);
    setReg8(PTBDD, 0x00);

do{
     //clr_ENABLE();
     clr_A0();
     set_WR();
     set_ENABLE();
     NOP();
     }while(lcd_data & status_busy);   //mask it dubug
    clr_ENABLE();
    setReg8(PTBDD, 0xFF);

}

Is that right? thank you!

Re: When the I / O output switch input , I have encountered...

xiaolin_gao — Sat, 10 Jan 2009 23:36:02 GMT

hi,kef.

Thank you very much for the help, I will have to crazy