4.3.1 Memory mapper
MPX
TM
has two memory mappers for mapping physical memory segments to a bank, a logical
space. Each segment's size is 16KB and maximum 32 segments are available. You can assign a
segment number to a bank via a 5-bit memory mapper register (REG_MAP0 and 1). Note that some
part of the bank 0 is occupied by special registers, you can't read or write memory contents of that
range. If needed, you can access all memory contents without such a limitation via bank 1.
4.3.2 Audio control registers
The audio CODEC and DAC are controlled directly by REG_CODEC and REG_DAC registers.
Detail descriptions are found on each chip vendor's site. Refer to VS1053B and WM8985 reference
manuals.
4.3.3 Special registers
MPX
TM
has two special registers to control and monitor internal system. Refer to Table 2: status
register and Table 3: control register for details. Note that all internal registers including mapper
registers are prohibited to application programs basically, however MSX is an open architecture and
it's free for personal use.
bit
name
description
7
VS_DREQ
‘
1’: CODEC data request, ‘0’: CODEC is busy
6
FIFO_RDY
‘
1’: FIFO available (minimum 512 bytes burst write acceptable)
5
FIFO_NEF
‘
1’: FIFO not empty
4
ID1
'0'
3
ID0
'0'
2
IRQ
‘
1’: Interrupt requested
1
SPI1_BUSY
‘
1’: DAC SPI I/F busy
0
SPI0_BUSY
‘
1’: CODEC SPI I/F busy
Table 2: status register
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