User Manual

VS1003
10 VS1003 REGISTERS
10.13.9 UserCodec, 0x0
Normally contains the following VS_DSP assembly code:
jr
nop
If the user wants to take control away from the standard decoder, the first instruction should be
replaced with an appropriate j command to user’s own code.
Unless the user is feeding MP3 or WMA data at the same time, the system activates the user
program in less than 1 ms. After this, the user should steal interrupt vectors from the system,
and insert user programs.
10.14 System Vector Functions
The System Vector Functions are pointers to some functions that the user may call to help
implementing his own applications.
10.14.1 WriteIRam(), 0x2
VS_DSP C prototype:
void WriteIRam(register __i0 u_int16 *addr, register __a1 u_int16 msW, register __a0 u_int16
lsW);
This is the preferred way to write to the User Instruction RAM.
10.14.2 ReadIRam(), 0x4
VS_DSP C prototype:
u_int32 ReadIRam(register __i0 u_int16 *addr);
This is the preferred way to read from the User Instruction RAM.
A1 contains the MSBs and a0 the LSBs of the result.
Version: 1.08, 2014-12-19 58