Originally Posted by prstein
You can use page writes with the AT24C1024, could that help?
Features
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• 256-byte Page Write Mode (Partial Page Writes Allowed)
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You can use page writes with the AT24C1024, could that help?
Features
• ...
• 256-byte Page Write Mode (Partial Page Writes Allowed)
• ...
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
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If eight pins is too much you could use a 4 bit interface.
Still much faster than any I2C or serial EEPROM, particularly when you
have to wait 10ms after a write cycle.
If you read a value and then update that value, you are supposed to wait 10ms right there.
No reason why the pic acting as a RAM chip couldn't perform other tasks until
it is interrupted,
as long as there's enough RAM left in both chips to run the program as well.
I'm sure I've asked about external RAM on this board before (or on the old picbasic list).
It would be nice to have a fast pic compatible RAM chip, as well as an FPU
(another thing I've asked about).
I'm sad that the pic32 chips don't even have an FPU (something I expected).
Last edited by Art; - 2nd March 2010 at 23:50.
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Not to keep beating the same drum ...
I suggest you look at something like the 23A640. You can do sequential reads and sequential writes. And all this over SPI. At 10MHz (and four lines - max), a 32-bit transfer is 3.2uS (that should be pretty fast).
From datasheet:
If operating in Sequential mode, the data stored in the memory at the next address can be read sequentially by continuing to provide clock pulses. The internal Address Pointer is automatically incremented to the next higher address after each byte of data is shifted out. When the highest address is reached (1FFFh), the address counter rolls over to address 0000h, allowing the read cycle to be continued indefinitely.This, or something similar, should fit your needs.If operating in Sequential mode, after the initial data byte is shifted in, additional bytes can be clocked into the device. The internal Address Pointer is automatically incremented. When the Address Pointer reaches the highest address (1FFFh), the address counter rolls over to (0000h). This allows the operation to continue indefinitely, however, previous data will be overwritten.
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Hi Art,
I think the hardware SPI port might do it. I'm going to try these: http://www.mouser.com/ProductDetail/...1pcR43MBP1g%3d. I don't care so much that they're non-volatile but they are much faster at writing than standard EEPROM.
Best,
Paul
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Yeap, I must have been smoking something. No way to fit it in.I still think you should have more than enough storage on an 18F452.
The part you highlighted is very cool (fast as SRAM, but non-volatile like SEEPROM). The 16k part will be great for 1024 WORDS, but will only fit half of the 1204 LONGS.
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Followup
Just wanted to followup with news of success. After a comedy of wiring errors I finally got an F-RAM going using shiftin and shiftout. Once I confirmed that as working I changed the code to use the hardware SPI port. It is blazingly fast. I'm using running the 18F452 at 20MHz so I can "only" run with a 5MHz clock. Haven't actually timed it (yet) but I think it'll all work out just fine.
If there's any interest I'll post the code in the Code Examples section.
Thanks again, everyone, for all the suggestions.
Best Regards,
Paul
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I have used the i2c version of the FRAM and liked it. I had to switch when I needed more memory, though... it can cost over 10x the price of an atmel eeprom.
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Hi Paul: I am actually trying to figure out the hardware SPI module for F-RAM. So can you share your codes for that part? I appreciate it very much!!!
Vinson
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Hello Vinson,
Here it is, warts and all...
Let us know if there are questions or difficulties.Code:'**************************************************************** '* Name : HW_FRAM_SPI_Test.pbp * '* Notes : Demo of using hardware SPI port to read and write * '* : a Ramtron FM25C106-G 16K 5V F-RAM chip. * '* : * '* : Assembled on an Olimex DEV-00021 40-pin * '* : board from Sparkfun. * '* : * '* : Much information on working with the hardware * '* : SPI was gleaned from Jeremy Grotte's * '* : sdfshc32d.pbp file. * '* : * '* : Compiled using PBP v2.60L * '* : * '**************************************************************** ' PIC18F452 DIP Package ' Pin Assignments ' Pin # Use Hookup ' 1 MCLR/VPP To Vdd through 4.7k resistor ' 2 RA0/AN0 n/c, reserved for analog input ' 3 RA1/AN1 n/c ' 4 RA2/AN2/VREF- n/c ' 5 RA3/AN3/VREF+ n/c ' 6 RA4/T0CKI n/c ' 7 RA5/AN4/SS n/c ' 8 RE0/RD/AN5 n/c ' 9 RE1/WR/AN6 n/c ' 10 RE2/CS/AN7 n/c ' 11 Vdd Power, +5V ' 12 Vss Ground ' 13 OSC1/CLKIN To 20MHz crystal ' 14 OSC2/CLKOUT To 20MHz crystal ' 15 RC0/T1OSO/T1CKI n/c ' 16 RC1/T1OSI/CCP2 n/c ' 17 RC2/CCP1 n/c ' 18 RC3/SCK/SCL to F-RAM SCK (pin 6) ' 19 RD0/PSP0 n/c ' 20 RD1/PSP1 n/c ' 21 RD2/PSP2 n/c ' 22 RD3/PSP3 FRAM_CS, to F-RAM CS (pin 1) ' 23 RC4/SDI/SDA SDI, to F-RAM SO (pin 2) ' 24 RC5/SDO SDO, to F-RAM SI (pin 5) ' 25 RC6/TX/CK TX; to MAX232A Pin 11 (goes out from pin 14 to DB9F pin 2) ' 26 RC7/RX/DT RX; to MAX232A Pin 12 (goes out from pin 13 to DB9F pin 3) ' 27 RD4/PSP4 n/c ' 28 RD5/PSP5 n/c ' 29 RD6/PSP6 n/c ' 30 RD7/PSP7 n/c ' 31 Vss Ground ' 32 Vdd Power, +5V ' 33 RB0/INT n/c ' 34 RB1 n/c ' 35 RB2 n/c ' 36 RB3/PGM n/c ' 37 RB4 n/c ' 38 RB5 n/c ' 39 RB6/PGC n/c ' 40 RB7/PGD n/c 'Notes '----- 'SETUP RS232: 'Target device uses 115200 baud, 8 bits, 1 stop bit, flow control = none '-------------------------------------------------------------------------------- '### Includes '-------------------------------------------------------------------------------- 'none '-------------------------------------------------------------------------------- '### Defines '-------------------------------------------------------------------------------- DEFINE LOADER_USED 1 DEFINE OSC 20 'Set receive register to receiver enabled DEFINE HSER_RCSTA 90h 'Set transmit register to transmitter enabled, high speed BRGH DEFINE HSER_TXSTA 24h 'Set baud rate DEFINE HSER_BAUD 115200 'automatically clear any USART overflows DEFINE HSER_CLROERR 1 '-------------------------------------------------------------------------------- '### Constants '-------------------------------------------------------------------------------- TRUE CON 1 FALSE CON 0 OCWREN con %00000110 'F-RAM Write Enable Op-Code OCRDSR con %00000101 'F-RAM Read Status Register Op-Code OCWRSR con %00000001 'F-RAM Write Status Register Op-Code OCREAD con %00000011 'F-RAM Read Memory Op-Code OCWRITE con %00000010 'F-RAM Write Memory Op-Code '-------------------------------------------------------------------------------- '### Aliases '-------------------------------------------------------------------------------- SCK Var PORTC.3 ' SPI clock SCK_TRIS Var TRISC.3 ' SPI clock direction SDI Var PORTC.4 ' SPI data in SDI_TRIS Var TRISC.4 ' SPI data in direction SDO Var PORTC.5 ' SPI data out SDO_TRIS Var TRISC.5 ' SPI data out direction FRAM_CS Var PORTD.3 ' F-RAM chip select FRAM_CS_TRIS Var TRISD.3 ' F-RAM chip select direction WCOL Var SSPCON1.7 ' SSP write collision SSPEN Var SSPCON1.5 ' SSP enable SSPIF Var PIR1.3 ' SSP interrupt flag '-------------------------------------------------------------------------------- '### Set Up Registers '-------------------------------------------------------------------------------- ADCON1 = %10001110 'left justified, RA0/AN0 is analog input 'Set up SPI port SSPSTAT = %01000000 ' Sample at middle of data output time, Transmit on idle rising edge of SCK 'SSPCON1 = %00000010 ' SPI master mode, clock = Fosc/64, Clock idle LOW. 'SSPCON1 = %00000001 ' SPI master mode, clock = Fosc/16, Clock idle LOW. SSPCON1 = %00000000 ' SPI master mode, clock = Fosc/4, Clock idle LOW. SSPEN = 1 ' Enable hardware SPI port. '-------------------------------------------------------------------------------- '### Variables '-------------------------------------------------------------------------------- nSPI_Data_In var byte nSPI_Data_Out var byte lVal var long wFRAM_Addr var word '-------------------------------------------------------------------------------- '### Initialization '-------------------------------------------------------------------------------- FRAM_CS = 1 ' F-RAM chip not selected. FRAM_CS_TRIS = 0' F-RAM chip select as output SDO = 1 ' Start SPI data out high SDO_TRIS = 0 ' SPI data out as Output SDI_TRIS = 1 ' SPI data in as Input SCK = 0 ' SPI clock idles low SCK_TRIS = 0 ' SPI clock as Output wFRAM_Addr = $000F ' Set an arbitray memory location lVal = -5000 ' Set lVal to some starting point pause 500 hserout["lVal initalized to ", dec lVal,13,10] 'Jump to Main program goto main '-------------------------------------------------------------------------------- '### Helper Functions '-------------------------------------------------------------------------------- WriteSPI: WCOL = 0 nSPI_Data_In = SSPBUF ' Clear the buffer. SSPIF = 0 ' Clear the interrupt flag. SSPBUF = nSPI_Data_Out ' Send the byte. If (WCOL) Then Return ' Check for write collision. While (!SSPIF) ' Wait for send to complete. Wend Return ReadSPI: nSPI_Data_In = SSPBUF ' Clear the buffer. SSPIF = 0 ' Clear the interrupt flag. SSPBUF = $ff ' Shift out a dummy byte. While (!SSPIF) ' Wait for receive byte. Wend nSPI_Data_In = SSPBUF ' Get the byte. return '-------------------------------------------------------------------------------- '### MAIN PROGRAM '-------------------------------------------------------------------------------- Main: ' Do a write ' Select the F-RAM FRAM_CS = 0 ' Begin with WREN nSPI_Data_Out = OCWREN gosub WriteSPI ' un-select the F-RAM FRAM_CS = 1 ' only one Op-code per chip select!!! ' Select the F-RAM FRAM_cs = 0 ' Next send WRITE OpCode nSPI_Data_Out = OCWrite gosub WriteSPI ' Send two bytes of address (upper 5 bits are "don't care") nSPI_Data_Out = wFRAM_Addr.HighByte '$00 gosub WriteSPI nSPI_Data_Out = wFRAM_Addr.LowByte '$0f gosub WriteSPI ' next byte(s) are data, address will increment with each write nSPI_Data_Out = lVal.Byte0 gosub WriteSPI nSPI_Data_Out = lVal.Byte1 gosub WriteSPI nSPI_Data_Out = lVal.Byte2 gosub WriteSPI nSPI_Data_Out = lVal.Byte3 gosub WriteSPI ' un-select the F-RAM FRAM_CS = 1 ' do a read FRAM_CS = 0 ' Begin by sending the read OpCode nSPI_Data_Out = OCREAD '=READ command gosub WriteSPI ' Send two bytes of address (upper 5 bits are "don't care") nSPI_Data_Out = wFRAM_Addr.HighByte gosub WriteSPI nSPI_Data_Out = wFRAM_Addr.LowByte gosub WriteSPI ' Now read in the value one byte at a time gosub ReadSPI 'one byte into nSPI_Data_In lVal.Byte0 = nSPI_Data_In gosub ReadSPI 'one byte into nSPI_Data_In lVal.Byte1 = nSPI_Data_In gosub ReadSPI 'one byte into nSPI_Data_In lVal.Byte2 = nSPI_Data_In gosub ReadSPI 'one byte into nSPI_Data_In lVal.Byte3 = nSPI_Data_In FRAM_CS = 1 hserout["lVal=",dec lVal,13,10]; ' Add one and write it back to the same location lVal = lVal + 1 goto Main
Best Regards,
Paul
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Actually I could use SHIFTIN and SHIFTOUT for accessing the F-RAM memory, as you told, it is a "comedy" wiring error, it seems like totally reversed. But for hardware SPI, I think the MISO,MOSI connection should be followed, right? In your code, it is connected like this.
Vinson
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The only thing I don't like about SHIFTIN/SHIFTOUT is that they are so slow. But following advice from another thread (several threads actually) about SPI I used them to make sure everything was working in some fashion before I stepped up to the hardware SPI. Reversing the MISO/MOSI connections was just one of the many errors I started with. (I also spent an hour trying to figure out why I couldn't get *any* response from the F-RAM; turns out I hadn't actually installed the chip yet!)
Best Regards,
Paul
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