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beaker404
Joined: 24 Jul 2012
Posts: 163
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| SPI 16B address and 8b data |
 Posted: Mon Aug 15, 2022 12:20 pm |
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CCS 5.064
PIC18F26K22
EEPROM 93LC66C
Looked around the forum and nothing came out as an exact solution to my problem,
problem being, using a 93LC66 in 8b data mode so 512 x 8 bytes.
Communication is via SPI and works find IF I stay below an address of 255
and I know why, the SPI is only sending 8b of address, tried sending MSB and LSB of the address word, did not work.
Is there a way to get a 16b address to the EEPROM followed by the 8b data? Perhaps I just do not get SPI well enough to resolve it.
SPI set up like this: for 8b data, this all works just not when I try to do 16b addressing.
| Code: |
#DEFINE SPI_XFER_9356(x) spi_xfer(SPI2_EEPROM, x)
#DEFINE EEPROM_ADDRESS unsigned long
#use spi(master, DO=Pin_B3, CLK=PIN_B1, DI=PIN_B2 ,ENABLE_ACTIVE=1, ENABLE_DELAY=20,mode=0, baud=2000000, stream=SPI2_EEPROM, bits=8, FORCE_SW) |
my write function:
| Code: | void write_ext_eeprom(EEPROM_ADDRESS address, BYTE data)
{
disable_interrupts(global);
output_high(EEPROM_SELECT);
SPI_XFER_9356(0xa);
SPI_XFER_9356(address);
SPI_XFER_9356(data);
output_low(EEPROM_SELECT);
delay_ms(11);
enable_interrupts(global);
} |
my read function:
| Code: | BYTE read_ext_eeprom(EEPROM_ADDRESS address)
{
BYTE data;
disable_interrupts(global);
output_high(EEPROM_SELECT);
SPI_XFER_9356(0xc);
SPI_XFER_9356(address);
data=SPI_XFER_9356(0);
output_low(EEPROM_SELECT);
enable_interrupts(global);
return(data);
} |
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beaker404
Joined: 24 Jul 2012
Posts: 163
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| Posted: Mon Aug 15, 2022 12:22 pm |
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| sorry for the poor formatting of the thread, for some reason I cannot edit it now correctly. |
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gaugeguy
Joined: 05 Apr 2011
Posts: 303
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| Posted: Mon Aug 15, 2022 12:43 pm |
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To access addresses 256-511, the high address bit is the low bit of the command.
| Code: |
output_high(EEPROM_SELECT);
SPI_XFER_9356(0x0c | 0x01); // command and high bit of address
SPI_XFER_9356(address); // low 8 bits of address
data=SPI_XFER_9356(0);
output_low(EEPROM_SELECT);
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beaker404
Joined: 24 Jul 2012
Posts: 163
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| Posted: Mon Aug 15, 2022 1:14 pm |
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thanks.
Not sure how I missed that in the datasheet, |
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