ISD3900
Publication Release Date: Dec 10, 2013
- 75 -
Revision 1.5
13.3
D
IGITAL
M
EMORY
C
OMMANDS
.
This section describes the 4 digital data commands that can be sent to the device. Digital commands
are ones that read, write or erase data directly in the flash memory through a separate interface than
the audio data command interface. Digital memory commands other than erase, can occur
simultaneously with audio memory commands.
13.3.1 Digital Read
DIG_READ
Byte
Sequence:
Host controller
0xA2
A[23:16]
A[15:8]
A[7:0]
0xXX
… 0xXX
ISD3900
Status
Status
Status
Status
D0
… Dn
Description:
Initiates a digital read of memory from address A[23:0].
Interrupt
Generation:
ADDR_ERR if memory protected or RDY/BSYB violated. OVF_ERR if read past
end of array.
This command initiates a read of flash memory from address A[23:0]. Following the three address
bytes, data can be read out of memory in a sequential manner. The RDY/BSYB pin is used to control
flow of data. If RDY/BSYB pin goes low, transfer must be paused until RDY/BSYB pin returns high.
The user should check RDY/BSYB pin before every byte is sent/read including the command and
address bytes. As many bytes of data as required can be read, command is terminated by raising SSB
high, finishing the SPI transaction. If an attempt is made to read past the end of memory, status byte
will be read back.
The command will always be accepted and RDY/BSYB pin will go low until any active digital memory
command is complete. If a digital read is attempted in read protected memory, status byte will be read
back and an ADDR_ERR interrupt will be generated. If a read past the end of memory is attempted an
OVF_ERR interrupt will be generated. If RDY/BSYB is violated then zero data will be read back and
an ADDR_ERR interrupt will be generated.
Please note that for ISD3900 Digital Read operation can only support up to 64M bits. User should
avoid trying to read memory beyond 64Mbit boundary.
13.3.2 Digital Write
DIG_WRITE
Byte
Sequence:
Host controller
0xA0
A[23:16]
A[15:8]
A[7:0]
D0
…
Dn
ISD3900
Status
Status
Status
Status
Status
…
Status
Description:
Initiates a digital write to memory from address A[23:0].
Interrupt
Generation:
ADDR_ERR if memory protected or RDY/BSYB violated. OVF_ERR if write past end
of array.