ARM IM-AD1 - Manual (Page 63)

Reference Design Example
ARM DUI 0163B Copyright © 2001-2003. All rights reserved. 4-17
4.7 Stepper motor peripheral
The example design instantiates two stepper controller blocks, each of which has two
stepper motor controllers. Stepper A controls the Step 1 and 2 interfaces which are
connected to the L298 stepper motor drivers. Stepper B controls the Step 3 and 4
interfaces which are connected at logic level to the connectors J21 and J22.
Each controller contains three registers, as shown in Table 4-10. These define phase
sequence generation, speed, and number of steps to rotate. The stepper motor controller
is clocked from PCLK to keep it synchronous with the APB. The step speed register is
fed with a 10kHz clock (which is divided down from the 4MHz IM_CLK signal) to
control the speed of the motor.
Each of the registers is double buffered, allowing a new value to be written to a holding
register while a previous count continues. Write to the STEPxCOUNT and
STEPxSPEED register locations first and then follow this with a write to the
STEPxCONT register. The controller loads the new values into the target registers when
the current count completes.
Table 4-10 Stepper motor registers
Offset
address
Name Access Function
0x0B00000 STEP1CONT Read/write Stepper 1 control register
0x0B00004 STEP1COUNT Read/write Stepper 1 step count register
0x0B00008 STEP1SPEED Read/write Stepper 1 Clock divider register
0x0B00010 STEP2CONT Read/write Stepper 2 controller register
0x0B00014 STEP2COUNT Read/write Stepper 2 step count register
0x0B00018 STEP2SPEED Read/write Stepper 2 Clock divider register
0x0C00000 STEP3CONT Read/write Stepper 3 control register
0x0C00004 STEP3COUNT Read/write Stepper 3 step count register
0x0C00008 STEP3SPEED Read/write Stepper 3 Clock divider register
0x0C00010 STEP4CONT Read/write Stepper 4 controller register
0x0C00014 STEP4COUNT Read/write Stepper 4 step count register
0x0C00018 STEP4SPEED Read/write Stepper 4 Clock divider register