SPC700/Driver Upload: Difference between revisions

Revision as of 23:07, 2 July 2023

In order to use main audio (Blargg's trick notwithstanding), the 5A22 must first upload a sound driver to the SPC700 over the following four ports:


Official Port Name	Port Name (SPC side)	Port Address (SPC side)	Port Name (5A22 side)	Port Address (5A22 side)	Data	Notes
PORT0	CPUIO0	00F4h	APUIO0	2140h	The SPC IPL writes AAh here when ready kick and kickback (as described by fullsnes) also go through here	PT0 is Nintendo's official name for the data the 5A22 writes to this port
PORT1	CPUIO1	00F5h	APUIO1	2141h	The SPC IPL writes BBh here when ready The 5A22 writes which command ("transfer" or "entry" as described by fullsnes) it wants the IPL to run here The SPC700 driver code is uploaded through here too	When the IPL is interpreting the value from this port as a command, zero means "jump to the entrypoint in the driver we just uploaded" and non-zero means "get ready to receive another block transfer"
PORT2	CPUIO2	00F6h	APUIO2	2142h	The 5A22 writes the low byte of the upload destination ARAM address here The 5A22 writes the low byte of the entrypoint into the SPC program here after all blocks have been uploaded
PORT3	CPUIO3	00F7h	APUIO3	2143h	The 5A22 writes the high byte of the upload destination ARAM address here The 5A22 writes the high byte of the entrypoint into the SPC program here after all blocks have been uploaded

The official Super Nintendo development manual describes the driver upload process in Appendix D of Book I. [1] Fullsnes has pseudocode for the upload procedure in https://problemkaputt.de/fullsnes.htm#snesapumaincpucommunicationport, and anomie's SPC700 Doc also lists a very similar 11 step procedure.

For the purposes of uploading to the SPC, the sound driver SPC700 machine code is divided into some number of contiguous data blocks. Each block has a four byte header which consists of:

the block size (2 bytes)
the target address where the block will end up in ARAM (another 2 bytes) [2]

References

[1] https://archive.org/details/SNESDevManual/book1/page/n236
[2] page D-3 "Data Block Organization" of the official dev manual

@@ Line 3: / Line 3: @@
 {| class="wikitable"
 |-
-! Official Port Name !! Port Name (SPC side) !! Port Address (SPC side) !! Port Name (5A22 side) !! Port Address (5A22 side) !! Data
+! Official Port Name !! Port Name (SPC side) !! Port Address (SPC side) !! Port Name (5A22 side) !! Port Address (5A22 side) !! Data !! Notes
 |+
-| PORT0 || CPUIO0 || 00F4h || APUIO0 || 2140h || The [[SPC IPL]] writes AAh here when ready, kick and kickback (as described by [[fullsnes]]) also go through here.  '''PT0''' is Nintendo's official name for the data the 5A22 writes to this port.
+| PORT0 || CPUIO0 || 00F4h || APUIO0 || 2140h ||
+* The [[SPC IPL]] writes AAh here when ready
+* kick and kickback (as described by [[fullsnes]]) also go through here
+|| '''PT0''' is Nintendo's official name for the data the 5A22 writes to this port
 |+
-| PORT1 || CPUIO1 || 00F5h || APUIO1 || 2141h || The SPC IPL writes BBh here when ready, the 5A22 writes which command ("transfer" or "entry" as described by fullsnes) it wants the IPL to run here, and the driver data is uploaded through here too
+| PORT1 || CPUIO1 || 00F5h || APUIO1 || 2141h ||
+* The SPC IPL writes BBh here when ready
+* The 5A22 writes which command ("transfer" or "entry" as described by fullsnes) it wants the IPL to run here
+* The SPC700 driver code is uploaded through here too
+|| When the IPL is interpreting the value from this port as a command, zero means "jump to the entrypoint in the driver we just uploaded" and non-zero means "get ready to receive another block transfer"
 |+
-| PORT2 || CPUIO2 || 00F6h || APUIO2 || 2142h || The 5A22 writes the low byte of the upload destination ARAM address here, and the low byte of the entrypoint into the SPC program once all blocks have been uploaded
+| PORT2 || CPUIO2 || 00F6h || APUIO2 || 2142h ||
+* The 5A22 writes the low byte of the upload destination ARAM address here
+* The 5A22 writes the low byte of the entrypoint into the SPC program here after all blocks have been uploaded
+||
 |+
-| PORT3 || CPUIO3 || 00F7h || APUIO3 || 2143h || The 5A22 writes the high byte of the upload destination ARAM address here, and the high byte of the entrypoint into the SPC program once all blocks have been uploaded.
+| PORT3 || CPUIO3 || 00F7h || APUIO3 || 2143h ||
+* The 5A22 writes the high byte of the upload destination ARAM address here
+* The 5A22 writes the high byte of the entrypoint into the SPC program here after all blocks have been uploaded
+||
 |}