Maxim Integrated 78M6631 - Manual (Page 19)

UG_6631_078 78M6631 Firmware Description Document
Rev 2 19
5 Register Descriptions
All register are 32 bits (4 bytes) and are on ”longword” (4 byte) boundaries. All register addresses are the
same internally for both SPI and CLI (UART) user interfaces. However, the SPI interface has the ability to
address individual bytes while the CLI interface can only address entire longwords. So SPI addresses
contain two extra low order bits.
5.1 Command Register
Command register can be accessed through UART/CLI (address 0x42) or SPI (address 0x108). The
Command Register allows the user to select voltage or current channels to be calibrated. Also allows
enabling or disabling of harmonic/fundamental measurements. The following table shows the Command
Register bit assignment. The default value of the Command Register is 0x00000000.
Bit Name
Flash
Stored
Description
31 – N CE reserved
30:28 – N MPU reserved
27 CO N Calibrate Offset
26 VA N Select VA Channel For Calibration
25 VB N Select VB Channel For Calibration
24 VC N Select VC Channel For Calibration
23 - N Not Used
22 IA N Select IA Channel For Calibration
21 IB N Select IB Channel For Calibration
20 IC N Select IC Channel For Calibration
19 CG N Calibrate Gain Command (1=calibrate)
18 CT N Calibrate Temperature
17:6 – N/A MPU reserved
5 FUND Y
Enable Fundamental/Harmonic
Calculations
4 FREQ Y
Allow Frequency to set Sine/Cosine
period
3 LINELOCK Y Locks low rate period to line cycles
2 YD
Y Selects DELTA / WYE Configuration
0=Wye ; 1=Delta
1:0 – N/A CE reserved