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khalis
Joined: 12 Feb 2009
Posts: 54
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| External EEPROM (25AA1024) |
 Posted: Tue Sep 29, 2009 8:25 pm |
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Hi
I have problem to read electronic signature from the device. Currently, I'm just testing the coding using Proteus 7.2 SP6. I'm using compiler 4.084 and PIC18F252.
Hope somebody can give some idea towards this matter.
Thank you
The coding I made as below
| Code: |
#include <18F252.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP, NOBROWNOUT, PUT
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
// SPI modes
#define SPI_MODE_0 (SPI_L_TO_H | SPI_XMIT_L_TO_H)
#define SPI_MODE_1 (SPI_L_TO_H)
#define SPI_MODE_2 (SPI_H_TO_L)
#define SPI_MODE_3 (SPI_H_TO_L | SPI_XMIT_L_TO_H)
void main()
{
int8 data;
setup_spi(SPI_MASTER | SPI_MODE_1 | SPI_CLK_DIV_16);
//Deep Power-Down mode
output_low(PIN_C2);
spi_write(0xB9);
output_high(PIN_C2);
//RELEASE FROM DEEP POWER-DOWN AND READ ELECTRONIC SIGNATURE
output_low(PIN_C2);
spi_write(0xAB);
spi_write(0x00);
spi_write(0x00);
spi_write(0x01);
data = spi_read(0x00); //read electronic signature
output_high(PIN_C2);
//Display data read from 25AA1024
printf("Data = %x\r",data); //view electronic signature
}
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 29, 2009 8:46 pm |
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| Quote: |
setup_spi(SPI_MASTER | SPI_MODE_1 | SPI_CLK_DIV_16);
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Your SPI mode is wrong. Look at the left side of this timing diagram on
page 5 of the 25AA1024 data sheet:
| Quote: | | FIGURE 1-2: SERIAL INPUT TIMING |
25AA1024 data sheet:
http://ww1.microchip.com/downloads/en/DeviceDoc/21836F.pdf
What SPI modes does show that it supports ? (They're shown in binary).
Choose one of the two modes and edit your setup_spi() statement. |
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khalis
Joined: 12 Feb 2009
Posts: 54
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| Posted: Tue Sep 29, 2009 8:58 pm |
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| I already change and try both modes - Mode 0,0 and 1,1 but still nothing appear in virtual terminal |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 29, 2009 9:32 pm |
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If it doesn't work in the two modes that it says are supported, then
look for another problem in your code. Don't try to communicate in
an unsupported mode.
Start to look for problems in your code. For example, in this table
on page 4, for parameter No. 21 (Tpd), it says the time from CS going
high, until Deep Power Down mode takes effect is 100 us max:
| Quote: | | TABLE 1-2: AC CHARACTERISTICS (CONTINUED) |
But your code puts the eeprom into Deep Power Down mode, and
then immediately tries to take it out of that mode again. I think you
should wait at least 100 us, before you try to take the chip out of
Deep Power Down mode. Try putting in a delay_us(200) statement
between the two operations.
Why did you choose a "dummy address" of 0x000001 ? I don't see
that in the data sheet. Why not use 0x000000 ? |
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khalis
Joined: 12 Feb 2009
Posts: 54
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| Posted: Tue Sep 29, 2009 10:32 pm |
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| I also tried put the delay between two operation as you suggested but still nothing displayed on the virtual terminal. The dummy address i used randomly. I thought it ok to use any numbers. It is possible the parameters of the eeprom in the proteus is not matching with the real one. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Sep 29, 2009 10:44 pm |
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How do you for certain that Proteus supports all commands for that
eeprom, and that they are all working correctly in your version of Proteus ? |
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khalis
Joined: 12 Feb 2009
Posts: 54
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| Posted: Wed Sep 30, 2009 12:00 am |
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That the main problem right now..i think i need to buy and do testing on the real chip..and from that i can debug the coding...  |
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