Changeset 67031cd in avrstuff

Timestamp:

Nov 18, 2012, 10:09:19 PM (11 years ago)

Author:

Adrien Destugues <pulkomandy@…>

Branches:

main

Children:

413443e

Parents:

7dcccbc

Message:

Try to erase and write a ROM (since we can't read the ID because of hardware limitations)

git-svn-id: ​svn://pulkomandy.tk/avrstuff@79 c6672c3c-f6b6-47f9-9001-1fd6b12fecbe

File:

• CPC stuff/gordon/manager/gordon.z80 (modified) (4 diffs)

CPC stuff/gordon/manager/gordon.z80

@@ -10 +10 @@
 ; get a bit messy so maybe we will need to use the screen at 4000 as a buffer
 ; for the ROM data as well. Or just use a bank for that ?
+        ; TODO
 
 ; Map the ROM in
-; TODO
+        LD BC, 0x7F85
+        OUT (C),C
 
 ; ask the user to enable writing
-; TODO
+        ; TODO
 
-; Check if we can read the ROM type
-        LD A, 0x90
+; Turns out with the MegaFlash design, we can't both read and write. When the
+; memory is in write mode, reading is disabled. This means we can't identify
+; the chip, or use the data polling features. And we have to go for the
+; worst-case timing given in the datasheet :(
+
+; ... anyway, start with erasing the sectors we need.
+        CALL 0xBD19
+        LD B, 4
+ERASE
+        PUSH BC
+
+        LD A, 0x80 ; ERASE
         CALL send_command
 
+        CALL prepare_command
+        
+        LD B,0xDF
+        LD C,5 ; ROM number to write (FIXME get it as a RSX param)
+        OUT (C),C
+
+        ; Compute address near start of sector
+        POP BC
+        LD A,B
+        DEC A
+        SLA A
+        SLA A
+        
+        ADD 0xC0
+
+        LD H,A
+
+        LD E, 0x30
+        LD (HL), E
+
+        ; This will delay long enough - we need at least 25ms
+        CALL 0xBD19
+
+        DJNZ ERASE
+
+; Ok, now that we erased the 4 sectors we needed, we can write data to them
         LD HL, 0xC000
+        LD IX, 0x4000
+PROGRAM
+        LD A, 0xA0 ; BYTE PROGRAM ;     2       10
+        PUSH HL                                   ;     3       13
+        CALL send_command                 ; 5   18
 
-        LD A,(HL)
-        CALL printhex
-        INC L
-        LD A,(HL)
-        CALL printhex
+        LD B,0xDF
+        LD C,5 ; ROM number to write (FIXME get it as a RSX param)
+        OUT (C),C
 
-        ; We should get 0x8F 87
-        ; TODO check that before continuing with writing the data
+        POP HL
+
+        LD A,(IX + 0)
+        LD (HL),A               ; Write occurs here. Need to wait 20 NOPs before next
+                                        ; operation on ROM. Our code is slow enough already !
+
+        INC HL                                  ;       2       2
+        INC IX                                  ;       3       5
+        JR NC, PROGRAM                  ;       3       8
+
         JR $
 
-        ; Now reuse and adapt the code from OUL guys !
+; Now reuse and adapt the code from OUL guys !
+        ; TODO
 
 ; That's all folks !
@@ -41 +91 @@
 
 ; Send a command to the ROM. The available commands are :
-ERASE           equ     0x80
+;ERASE          equ     0x80
 IDENTIFY        equ     0x90
 BYTEPROG        equ 0xA0
@@ -48 +98 @@
 ; Input: Commend to send in A register
 send_command:
+        ; That code is shared with sector erase which has some tricks
+        call prepare_command
+
+        ; Select ROM 1 again and write the command to address 0xEAAA
+        DEC C
+        OUT (C),C
+        EX DE,HL
+        LD (HL), A
+
+        RET
+
+prepare_command:
         ; Select ROM 1
         LD BC,0xDF01
@@ -62 +124 @@
         EX DE,HL
         LD (HL), E
-
-        ; Select ROM 1 again and write the command to address 0xEAAA
-        DEC C
-        OUT (C),C
-        EX DE,HL
-        LD (HL), A
 
         RET