Add SD card software interface

Adds a function to send a command to the sd card.
2022-04-10 17:55:51 -05:00
parent cd11670fb1
commit 7092cc8f77
4 changed files with 42 additions and 0 deletions
--- a/sw/sd_card.s
+++ b/sw/sd_card.s
@@ -0,0 +1,27 @@
+.include "io.inc65"
+
+.importzp sp, sreg
+
+.export _sd_card_command
+
+.autoimport on
+
+.code
+
+; Send sd card command.
+; command is in A register, the args are on the stack
+; I think the order is high byte first?
+_sd_card_command:
+    pha
+
+    jsr popeax
+    sta SD_ARG
+    stx SD_ARG+1
+    lda sreg
+    sta SD_ARG+2
+    lda sreg+1
+    sta SD_ARG+3
+
+    pla
+    sta SD_CMD
+    rts