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Part 2: Interfacing and Configuring
SE C T I O N 2 . 4
Using User-Defined SPI
The MDriveAC Plus can be configured and operated through the end-user's SPI interface without using the IMS
SPI Motor Interface software and optional parameter setup cable.
An example of when this might be used is in cases where the machine design requires parameter settings to be
changed on-the-fly by a software program or multiple system MDriveAC Plus Microstepping units parameter states
being written/read.
SPI Timing Notes
1. MSb (Most Significant bit) first and MSB (Most Significant Byte) first.
2. 8 bit bytes.
3. 25 kHz SPI Clock (SCK).
4. Data In (MOSI) on rising clock.
5. Data Out (MISO) on falling clock.
Check Sum Calculation for SPI
The values in the example below are 8-bit binary hexadecimal conversions for the following SPI parameters:
MRC=25%, MHC=5%, MSEL=256, HCDT=500 mSec, WARNTEMP=80.
The Check Sum is calculated as follows:
(Hex) 80+19+05+00+00+01+F4+50
Sum = E3 1110 0011
1’s complement = 1C 0001 1100 (Invert)
2’s complement = 1D 0001 1101 (Add 1)
Send the check sum value of 1D
Note: 80 is always the first command on a write.
Note: Once a write is performed, a read needs to be performed to see if there is a fault. The fault is the last byte of
the read.
Figure 2.4.1: SPI Timing