Datasheet

Note 17: Reading and writing the CPU ports by the serial interface is allowed while the CPU is executing its program. In the case of
simultaneous access of the ports by both the CPU and the serial interface, the CPU has priority. Although this procedure is
allowed, it is not recommended, as the serial interface may change values previously written by the CPU. If a “snapshot” of
the ports and module register contents is required while the CPU is running, halt the CPU, read the contents of the ports
and/or module registers, and restore the original port/module register values prior to starting the CPU again.
Table 38. Internal Register Set Address
(IRSA) Decoding
Table 39. Command Register (CR) Decoding
MAX1464 Low-Power, Low-Noise Multichannel
Sensor Signal Processor
www.maximintegrated.com
Maxim Integrated │ 42
IRSA[3:0]
REGISTER
NIBBLE
ADDRESSED
DESCRIPTION
0000 DHR[3:0] Write IRSD[3:0] to DHR[3:0].
0001 DHR[7:4] Write IRSD[3:0] to DHR[7:4].
0010 DHR[11:8] Write IRSD[3:0] to DHR[11:8].
0011 DHR[15:12] Write IRSD[3:0] to DHR[15:12].
0100 PFAR[3:0] Write IRSD[3:0] to PFAR[3:0].
0101 PFAR[7:4] Write IRSD[3:0] to PFAR[7:4].
0110 PFAR[11:8] Write IRSD[3:0] to PFAR[11:8].
0111 PFAR[15:12] Write IRSD[3:0] to PFAR[15:12].
1000 CR[3:0] Write IRSD[3:0] to CR[3:0].
1001 IMR[3:0] Write IRSD[3:0] to IR[3:0].
1010–1110 — Unused.
CR DESCRIPTION CPU HALTED
0000 Write 16-bit DHR contents into the CPU port specied by PFAR[3:0]. No (Note 17)
0001 Write 8-bit DHR[7:0] contents into FLASH memory location specied by PFAR[11:0]. Yes
0010 Read 16-bit CPU port specied by PFAR[3:0] into DHR. No (Note 17)
0011 Read 8-bit FLASH location specied by PFAR[11:0] into DHR[7:0]. Yes
0100 Read 16-bit CPU accumulator register (A) into DHR. Yes
0101
Read 8-bit FLASH location specied by the CPU program counter (PC) (CPU instruction or data) to
DHR[7:0].
Yes
0110 Read 16-bit CPU PC to DHR. Yes
0111 Halt the CPU. No
1000 Start the CPU, i.e., clear the HALT CPU bit from the current PC location. Yes
1001 Single step the CPU. Only one CPU clock cycle is executed. Yes
1010 Reset the PC to zero. Yes
1011 Reset the modules, FLASH controller, and CPU registers D, E, F. Yes
1100 No operation. —
1101 Erase a 64-byte “page” of FLASH as specied by PFAR[11:6]. Yes
1110 Erase the entire FLASH partition (4kB, PS0, or 128 bytes, PS1). Yes
1111
Change from FLASH partition PS0 to FLASH partition PS1 (128 byte auxiliary). A subsequent halt
CPU command resets the partition selection back to PS0.
Yes