Intelligent Motion Systems Motion Detector operating instructions PWM Control Bits

PWM Control Bits

Bit 0x0203 Read/Write Initial Value

7	6	5	4	3	2	1	0
QUIET		SYNC_EN	RECIR		TODLY[2:0]		ENABLE
R/W	R/W	R/W	R/W	R/W	R/W	R/W	R/W
0	0	1	0	0	0	1	0

Figure 2.6.16: PWM Control Bits

PWMCT

Bit 7 – QUIET

This bit changes PWM operation. When quiet is set, the bridge logic does not enter the reverse measure period, therefore there are fewer transitions. The bridge is disabled during zero cross. This mode is used at rest or when moving very slowly. When quiet is cleared, normal bridge operation is selected.

Bit 6 – Not used

Bit 5 – SYNC_EN

This bit controls the synchronization of the bridge PWM with the zero cross. When the sync_en bit is set, the bridge PWM will be synchronized with the positive front slope of the sin phase at each zero cross.

Bit 4 – RECIR

This bit controls where the motor current will recirculate within the bridge during the recirculate period. When recirc is set, the motor current will recirculate in the high portion of the bridge. When recir is cleared, the motor current will recirculate in the low portion of the bridge.

Bits 3..1 – TODLY - Turn on Delay

This value sets the bridge control turn on delay to prevent shoot through if a discrete FET bridge is in use. The range is 0 to 350 nS with 50 nS resolution. Each LSB is 50 nS. The default setting for a bridge driver is 50 nS (0x1).

Bit 0 – ENABLE

Bridge Enable, this bit is set at the factory and is inaccessible to the user.

Example PWM Settings By Motor Specifications

The following settings are based upon IMS settings per motor specifications and should serve as a baseline to work from with regard to the manufacturer specifications of the motor being utilized. Note that these are example settings ONLY!

Example PW Settings

Frame	Stack	Phase	Phase	Phase	MASK	Duty	Frequency	Checksum
		Current	Resistance	Inductance		Cycle
Size	Size				<mask>		<sfreq>	<chksum>
		(ARMS)	(Ω)	(mH)		<period>
14	Single	0.75	4.30	4	102	90	170	106
	Single	1.5	1.30	2.1	136	90	170	140
17	Double	1.5	2.10	5.0	136	90	170	140
	Triple	1.5	2.00	3.85	136	90	170	140
	Single
		2.4	0.95	2.4	136	90	170	140
23	Double	2.4	1.20	4.0	136	90	170	140
	Triple	2.4	1.50	5.4	136	90	170	140

MForce Default

—

—

—

204

95

170

—

Table 2.6.9: Example PWM Settings

40 Microstepping MForce PowerDrive Manual Revision R032008