Home : Analog Devices ADSP-21xx : ADSP-2189M Memory architecture
The ADSP-2189M has 192 Kbytes of internal RAM, divided into:
PM (Programme Memory)
- Used for the programme code.
- Word size = 24-bits.
- Address width = 14-bits (16 K).
- Total of 32 Kwords internal memory, but only 16 Kwords can be accessed at one time.
000016..1FFF16 Fixed 8 Kword of internal RAM. 200016..3FFF16 8 Kword page: any one of 3 internal pages (selected by PMOVLAY = 0,4,5) or 2 external pages (selected by PMOVLAY = 1,2). DM (Data Memory)
- Used for data storage.
- Word size = 16-bits.
- Address width = 14-bits (16 K).
- Total 48 of Kwords internal memory, but only 16 Kwords can be accessed at one time.
000016..1FFF16 8 Kword page: any one of 5 internal pages (selected by DMOVLAY = 0,4,5,6,7) or 2 external pages (selected by DMOVLAY = 1,2). 200016..3FFF16 Fixed 8 Kword of internal RAM. (Uppermost 32 words are actually memory mapped registers).
The ADSP-2189M can also access external memory:
Byte Memory
- Word size = 8-bits.
- Address width = 22-bits (4 M).
- Total of 4 Mbytes is accessible, as 256 pages of 16 Kbytes.
dm(3FE116) BDMA Internal Address
b15...b14 Unused (zero). b13...b0 Internal start address for DMA transfer. dm(3FE216) BDMA External Address
b15...b14 Unused (zero). b13...b0 Least significant 14-bits of external start address for DMA transfer. dm(3FE316) BDMA Control
b15...b8 Byte memory page, i.e. most significant 8-bits of external start address for DMA transfer. b7...b4 Selects the internal DM or PM overlay to read/write. b3 0 = programme continues execution during DMA transfer.
1 = context reset: halt execution, and restart from address 000016 when the DMA transfer completes.b2 0 = read from byte memory.
1 = write to byte memory.b1...b0 00 = read/write 24-bit words in PM.
01 = read/write 16-bit words in DM.
10 = read/write most sig. 8-bits in DM.
11 = read/write least sig. 8-bits in DM.dm(3FE416) BDMA Word Count
b15...b14 Unused (zero). b13...b0 Number of words to transfer: decrements to zero during the transfer.