BS2, SEROUT, and iPod. Help Needed!

SaltyDave

I'm trying to use the BS2 to remotely control my ipod via serial communication. I have a dock connector and all the wiring worked out, but the code is giving me issues. I found the ipod's communication protocol here: http://ipodlinux.org/Apple_Accessory_Protocol#iPod_Remote_.28Mode_2.29 but I still can't figure out what my SEROUT command needs to look like. I just want to be able to pause, play, skip forward, skip backward, and change the volume. Can anyone help me figure this out?

Beau Schwabe

Can you post your code so far?·

If I read the documentation correctly, the serial communication is a standard 8N1 protocol and the Baud needs to be at least 19.2k.· You should also be using TTL levels to communicate with.

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

SaltyDave

This is the program I'm using right now to try and figure things out:

Checksum VAR Byte
Length VAR Byte
Mode VAR Byte
Command1 VAR Byte
Command2 VAR Byte

Main:
Length = $03
Mode = $00
Command1 = $01
Command2 = $02
GOSUB Serial1

Length = $03
Mode = $02
Command1 = $00
Command2 = $02
GOSUB Serial1

Length = $03
Mode = $02
Command1 = $00
Command2 = $00
GOSUB Serial1

PAUSE 1000
GOTO Main

Serial1:
Checksum = $100 - ((Length+Mode+Command1+Command2)+$ff)
DEBUG "Checksum = ", HEX Checksum, " "
SEROUT 1, 16416, [noparse][[/noparse]$ff,$55,HEX Length,HEX Mode,HEX Command1,HEX Command2,HEX Checksum]
RETURN

From what I understand, this should switch the ipod to remote control mode and turn up the volume every second, but I get no response at all when I run it. I've tried to do some research on the 8n1 standard, but I feel like I'm still missing something there. As for TTL levels, I have no idea what that is. I've also tried using "32" for the baudmode instead of "16416", going by the calculations in the BS2 documentation, but that didn't work either.

Beau Schwabe

You don't need to use the·HEX formatter in the SERIAL·command when sending·data to another device, the HEX formatter is more·for·making·it "Human readable" when using·DEBUG.
Try this for the SEROUT line...
·
SEROUT 1, 16416, [noparse][[/noparse]$ff,$55,Length,Mode,Command1,Command2,Checksum]··· '.... Inverted
·
SEROUT 1, 32, [noparse][[/noparse]$ff,$55,Length,Mode,Command1,Command2,Checksum]··· '.... Non-Inverted
·
·
.... If you’re driving it from a STAMP, then the output is TTL (0V to 5V)· If you are driving it from your PC which you should not be doing without a proper voltage level shifter, the voltages can swing from -12V to 12V
·

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.