EEPROM writes and reads

[Paul Haug]

Well, most of the program is up and running, I can draw diagonal lines across the CRT by ramping both DACs from o to 255, now the next step is writing and reading the eeprom. I looked in the data sheets for the memory map but EEprom appears to be 0 to 255 address (no offset).
Any way here is a snippit of the code with the writes and my attempts to read and display on my LCD. All I get is 255 (0xff) from address 0 to 255 (not entirly, see below). The code here is shown only the part I need help on, it's getting too long to post the whole thing.
Any help on EEPROM and I think I will have this project under control.
'
'First, setup eeprom memory with data
' 16 bytes of Data per line, 16 lines for 256 bytes, can go
; to 256 bytes with PIC16F886 ChipFamily
' 'First byte Vert position, 2nd byte Horz position
EPWRITE 0, 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16
EPWRITE 16, 9,9,10,10,11,11,12,12,13,13,14,14,15,15,16,16
EPWRITE 32, 17,17,18,18,19,19,20,20,21,21,22,22,23,23,24,24
EPWRITE 48, 25,25,26,26,27,27,28,28,29,29,30,30,31,31,32,32
EPWRITE 64, 33,33,34,34,35,35,36,36,37,37,38,38,39,39,40,40
EPWRITE 80, 41,41,42,42,43,43,44,44,45,45,46,46,47,47,48,48
'
;----------------------------------------------------------------
; Read the eeprom bytes for test
testlp=0 ;intialize test loop

Do Forever
         for testlp=0 to 255
            EPRead testlp, AtoD_Value
       hserprint AtoD_Value  ;write value to LCD for testing
          wait 500 ms
         next testlp
 clear_screen   ;done all 256 bytes

 Loop

;
Well, additional checking showed the read is apparently working but something wrong with the writes, apparently I cannot delinate byte writes with just a comma. Found that location 0 had a one, location 16 had a nine, location 32 had a 17 and so forth, but all other locations had 255.
So apparently I can only write one byte per EPWRITE staement ??????? If so this is going to be clumsy.
Guess I will have to structure an aray and EPWRITE byte by byte from an array.

[Anobium]

Use a table. Look at the Help with the write to EEPROM option.

[William Roth]

Pointers should be implemented in the near future to allow multiple bytes with EPWRITE and others. In the mean time remember that GCB supports arrays. So first put the data in an array, then wrrite to EEPROM in a loop. Like this (Untested)

Dim EEData(16) ' // 16 Byte Array
Dim EEAddr as Byte
Dim ii as Byte '// Array Pointer

EEData = 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16 '// Put 16 bytes data in array
WriteData 0

EEdata = 9,9,10,10,11,11,12,12,13,13,14,14,15,15,16,16
WriteData 16

EEdata = 17,17,18,18,19,19,20,20,21,21,22,22,23,23,24,24
WriteData 32

EEdata = 25,25,26,26,27,27,28,28,29,29,30,30,31,31,32,32
WriteData 48

EEdata = 33,33,34,34,35,35,36,36,37,37,38,38,39,39,40,40
WriteData 64

EEdata = 41,41,42,42,43,43,44,44,45,45,46,46,47,47,48,48
WriteData 80

Sub WriteData (in EEAddr)
For ii = 1 to EEData(0) '// index 0 is numbytes in Array
EPWRITE EEAddr, EEdata(ii)
EEaddr++ '// Increment Address
Next
End Sub ,

[Anobium]

See http://gcbasic.sourceforge.net/help/_lookup_tables.html at the bottom of the page

[William Roth]

Remember after your code is tested and debugged and the EEPROM is loaded with Data , you must add a command line switch to IPECMD.exe to prevent the EEPROM from being erased upon subsequent programing.. The switch is -Z.

[William Roth]

Paul,

As Evan suggested, it is probably a better option to use a lookup table. A lookup table is easier to set up, easier to read, and can be read more than 10 times faster (literally) than EEPROM.
A single EEPROM read takes about 3.8 microseconds. A single Table read takes about 320 nano seconds. (16F@32Mhz)

Below is how I might Use/Test a table given the source code you provided. I used a PIC16F18855 so you will need to adapt for whatever chip you end up using.

Note: You do not need the PPS stuff in this Code. PPS is for PIC chips with Peripheral Pin Select capabilities.

; ----- Configuration
 #chip 16f18855,32
 #Config FEXTOSC_OFF, RSTOSC_HFINT32
 #Config WRT_OFF, CPD_ON, MCLRE_OFF
 #Option Explicit
 #startup INITPPS, 85

 ''' Define I2C settings
 #define hi2c_BAUD_RATE 400
 #define hi2c_Clock PORTC.3
 #define hi2c_Data PORTC.4

 Dir HI2C_DATA in
 Dir HI2C_CLOCK in
 HI2CMode Master

 ''' Set up LCD
 #define LCD_IO 10
 #define LCD_I2C_Address_1 0x7E
 #define LCD_SPEED SLOW
 #define LCD_Backlight_On_State  1
 #define LCD_Backlight_Off_State 0

 ''' variables
 Dim TableData as Byte
 Dim ii as Byte
 Dim location as byte
 Dim numbytes as byte

 ''' Table location  "0" always holds the number of bytes in the table
 ''' For example: Loc "0"  in the table below will hold a byte value of 80
 Table MyTable as Byte  '// 80 Bytes
       1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
       9, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16
       17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 24
       33, 33, 34, 34, 35, 35, 36, 36, 37, 37, 38, 38, 39, 39, 40, 40
       41, 41, 42, 42, 43, 43, 44, 44, 45, 45, 46, 46, 47, 47, 48, 48
End Table

'---- Main Program Begins Here -----
CLS '// Clear LCD Display

Do
    Locate 0,0           '// Start of LCD Line 0
    Read_MyTable (1,4)   '// read 4 bytes starting at location 1
    Locate 1,0           '// Start of LCD Line 1
    Read_MyTable(17,4)   '// read 4 bytes starting at location 17
    Locate 2,0           '// Start of LCD Line 2
    Read_MyTable(49,4)   '// read 4 bytes starting at location 49
    Locate 3,0           '// Start of LCD Line 3
    Read_MyTable(65,4)   '// read 4 bytes starting at location 65
    Wait  4 s
    CLS
    Wait 1 s
Loop

END

Sub Read_MyTable(location, numbytes)
       for ii = location to (location + numbytes -1)
          ReadTable MyTable, ii, TableData
          Print tableData : LCDSPACE 1
       next
End Sub

Sub InitPPS
UNLOCKPPS
    'Module: MSSP1
    RC3PPS = 0x0014        'SCL1 > RC3
    SSP1CLKPPS = 0x0013    'RC3 > SCL1 (bi-directional)
    RC4PPS = 0x0015        'SDA1 > RC4
    SSP1DATPPS = 0x0014    'RC4 > SDA1 (bi-directional)
LOCKPPS
End Sub

[Paul Haug]

Thanks guys, I did setup a lookup table and have it running. I had been thinking that the EEPROM was just sort of redundit and not useful in this application, since the data is always retained within the code itself, so the extra 256 bytes of EEPROM was not very useful in this application. I had not remembered EEprom speed, might be important for this application (CRT Updatei).
I can now draw simple shapes on the CRT but have a long way to go.
Again, Thanks.
Paul