Introduction:
Serial SRAM is a standalone volatile memory that provides an easy and inexpensive way to add more RAM to application. These are 8-pin low-power devices. They are high-performance devices have unlimited endurance and zero write times, making them ideal for applications involving continuous data transfer, buffering, data logging, audio, video, internet, graphics and other math and data-intensive functions.
These devices are available from 64 Kbit up to 1 Mbit in density and support SPI, SDI and SQI™ bus modes.
The GCBASIC library only supports SPI bus mode. The GCBASIC library supports hardware and software SPI - this is controlled via a constant, see below.
To use the SRAM libray simply include the following in your user code.
This will initialise the driver.
#define SPISRAM_CS Porta.2 'Also known as SS, or Slave Select
#define SPISRAM_SCK Portc.3 'Also known as CLK
#define SPISRAM_DO Portc.5 'Also known as MOSI
#define SPISRAM_DI Portc.4 'Also known as MISO
#define SPISRAM_HARDWARESPI
#define SPISRAM_TYPE SRAM_23LC1024SRAM memory operations.
The library exposes a set of method to support use of SRAM memory.
|
Method |
Parameters |
Usage |
|
SRAMWrite |
eepAddr as long, eepromVal as byte |
A subroutine that required the address and the value to be written to SRAM. |
|
SRAMRead |
eepAddr as long, eepromVal as byte |
A subroutine that required the address and variable to updated with the byte value from the specified SRAM address. |
|
SRAMRead |
eepAddr as long |
A function that required the address. The function returns a byte value from the specified SRAM address. |
The library requires a set of constants to support use of SRAM memory.
|
Constant |
Parameters |
Usage |
|
SPISRAM_TYPE |
Specifies the type of SRAM. |
Requires one of the following constants SRAM_23LC1024, |
|
SPISRAM_CS |
Specifies the port for the chip select port. |
Required |
|
SPISRAM_SCK |
Specifies the port for the SPI clock port. |
Required |
|
SPISRAM_DO |
Specifies the port for the SPI data out, or MOSI, port. |
Required |
|
SPISRAM_DI |
Specifies the port for the data in, or MISO, port. |
Required |
|
HWSPIMode |
Specifies the speed of the SPI communications for Hardware SPI only. |
Optional defaults to MASTERFAST. Options are MASTERSLOW, |
|
SPISRAM_HARDWARESPI |
Instructs the library to use hardware SPI, remove or comment out if you want to use software SPI. |
Optional |
The library also exposes a constant that is specific to the device.
These may be useful in the user program.
This constant is used by the library.
A user may use this public constant.
|
Constant |
Type |
Usage |
|
SPISRAM_CAPACITY |
Long value |
Use to determine the size of the SRAM device |
Examples
#include <uno_mega328p.h>
#option explicit
' USART settings
#define USART_BAUD_RATE 57600
#define USART_DELAY 0 ms
#define USART_BLOCKING
#define USART_TX_BLOCKING
'SD card attached to SPI bus as follows:
'
'UNO: MOSI - pin 11, MISO - pin 12, CLK - pin 13, CS - pin 4 (CS pin can be changed) and pin #10 (SS) must be an output
'Mega: MOSI - pin 51, MISO - pin 50, CLK - pin 52, CS - pin 4 (CS pin can be changed) and pin #52 (SS) must be an output
'Leonardo: Connect to hardware SPI via the ICSP header
#define SPISRAM_CS DIGITAL_5 'Also known as SS, or Slave Select
#define SPISRAM_SCK DIGITAL_13 'Also known as CLK
#define SPISRAM_DO DIGITAL_11 'Also known as MOSI
#define SPISRAM_DI DIGITAL_12 'Also known as MISO
#define SPISRAM_HARDWARESPI
#define SPISRAM_TYPE SRAM_23LC1024
#define HWSPIMode MASTERULTRAFAST 'MASTERSLOW | MASTER | MASTERFAST | MASTERULTRAFAST for specific AVRs only. Defaults to MASTERFAST
'********************************************************************************
'Main program
'Wait 2 seconds to open the serial terminal
wait 2 s
HSerPrintCRLF 2
HSerPrint "Writing..."
HSerPrintCRLF
For SRAM_location=0 to SPISRAM_CAPACITY - 1
SRAMWrite ( [long]SRAM_location, SRAM_location and 255 )
Next
dim spirambyteread as Byte
spirambyteread = 11
HSerPrintCRLF 2
dim SRAM_location as long
HSerPrint "Reading..."
HSerPrintCRLF
For SRAM_location=0 to SPISRAM_CAPACITY - 1
'choose one....
'SRAMread ( SRAM_location, spirambyteread )
'or, as a function
spirambyteread = SRAMread ( SRAM_location )
if spirambyteread = ( SRAM_location and 255 ) then
HSerPrint hex(spirambyteread)
else
HSerPrint "**"
end if
HSerPrint ":"
Next
HSerPrintCRLF
HSerPrint "Wait..."
HSerPrintCRLF
Wait 2 s
HSerPrint "Rewriting to 0x00 ..."
HSerPrintCRLF
For SRAM_location=0 to SPISRAM_CAPACITY - 1
SRAMWrite ( [long]SRAM_location, 0 )
Next
Dim errorcount as long
errorcount = 0
For SRAM_location=0 to SPISRAM_CAPACITY - 1
SRAMRead ( SRAM_location, spirambyteread )
if spirambyteread <> 0 then
errorcount++
end if
Next
HSerPrint "Error Count (should be 0) = "
HSerPrint errorcount
HSerPrintCRLF
HSerPrint "End..."
HSerPrintCRLF
endor, for a PIC with PPS
'Chip Settings.
#chip 18F47k42, 64
#config MCLRE = ON
#option explicit
'PPS Tool version: 0.0.5.27
'PinManager data: v1.78
'Generated for 18F47K42
'
'Template comment at the start of the config file
'
#startup InitPPS, 85
#define PPSToolPart 18F47K42
Sub InitPPS
'This has been added to turn off PPS SPI when in SPI software mode
#ifdef SPISRAM_HARDWARESPI
'Module: SPI1
RC3PPS = 0x001E 'SCK1 > RC3
SPI1SCKPPS = 0x0013 'RC3 > SCK1 (bi-directional)
RC5PPS = 0x001F 'SDO1 > RC5
SPI1SDIPPS = 0x0014 'RC4 > SDI1
'Module: UART pin directions
#endif
'Module: UART pin directions
Dir PORTC.6 Out ' Make TX1 pin an output
'Module: UART1
RC6PPS = 0x0013 'TX1 > RC6
End Sub
'Template comment at the end of the config file
' USART settings
#define USART_BAUD_RATE 57600
#define USART_DELAY 0 ms
#define USART_BLOCKING
#define USART_TX_BLOCKING
#define SPISRAM_CS Porta.2 'Also known as SS, or Slave Select
#define SPISRAM_SCK Portc.3 'Also known as CLK
#define SPISRAM_DO Portc.5 'Also known as MOSI
#define SPISRAM_DI Portc.4 'Also known as MISO
#define SPISRAM_HARDWARESPI
#define SPISRAM_TYPE SRAM_23LC1024
'********************************************************************************
'Main program
'Wait 2 seconds to open the serial terminal
wait 2 s
dim sizeofSPIRAM as long
sizeofSPIRAM = SPISRAM_CAPACITY
HSerPrintCRLF 2
HSerPrint "Writing...SPISRAM_CAPACITY = 0x"
HSerPrint hex(sizeofSPIRAM_U)
HSerPrint hex(sizeofSPIRAM_H)
HSerPrint hex(sizeofSPIRAM)
HSerPrintCRLF
wait 100 ms
dim SRAM_location as long
For SRAM_location=0 to SPISRAM_CAPACITY - 1
SRAMWrite ( [long]SRAM_location, SRAM_location and 255 )
Next
dim spirambyteread as Byte
spirambyteread = 11 'could be any number....
HSerPrintCRLF 2
HSerPrint "Reading..."
HSerPrintCRLF
For SRAM_location=0 to SPISRAM_CAPACITY - 1
'choose one....
'SRAMRead ( SRAM_location, spirambyteread )
'or, as a function
spirambyteread = SRAMRead ( SRAM_location )
if spirambyteread = ( SRAM_location and 255 ) then
HSerPrint hex(spirambyteread)
else
HSerPrint "**"
end if
HSerPrint ":"
Next
HSerPrintCRLF
HSerPrint "Wait..."
HSerPrintCRLF
Wait 2 s
HSerPrint "Rewriting to 0x00 ..."
HSerPrintCRLF
For SRAM_location=0 to SPISRAM_CAPACITY - 1
SRAMWrite ( [long]SRAM_location, 0 )
Next
Dim errorcount as long
errorcount = 0
For SRAM_location=0 to SPISRAM_CAPACITY - 1
SRAMRead ( SRAM_location, spirambyteread )
if spirambyteread <> 0 then
errorcount++
end if
Next
HSerPrint "Error Count (should be 0) = "
HSerPrint errorcount
HSerPrintCRLF
HSerPrint "End..."
HSerPrintCRLF
do
loop
