CS5460A
pulse, one of the output pins (either EOUT or
EDIR) changes state. When the CS5460A must is-
sue another energy pulse, the other output chang-
es state. The direction the motor will rotate is
determined by the order of the state changes.
When energy is positive, EOUT will lead EDIR
such that the EOUT pulse train will lead the EDIR
pulse train by ~1/4 of the periods of these two
pulse train signal. When energy is negative, EDIR
will lead EOUT in a similar manner. See Figure 12.
...
...
EOUT
...
...
EDIR
Positive Energy
Negative Energy
Figure 12. Stepper Motor Format on EOUT and EDIR
3.3 Auto-Boot Mode Using EEPROM
3.3.1 Auto-Boot Configuration
The CS5460A has a MODE pin. When the MODE
pin is set to logic low, the CS5460A is in normal op-
erating mode, called host mode. This mode de-
notes the normal operation of the part, that has
been described so far. But when this pin is set to
logic high, the CS5460A auto-boot mode is en-
abled. In auto-boot mode, the CS5460A is config-
ured to request a memory download from an
external serial EEPROM. The download sequence
is initiated by driving the RESET pin to logic high.
Auto-Boot mode allows the CS5460A to operate
without the need for a microcontroller. Note that if
the MODE pin is left unconnected, it will default to
logic low because of an internal pull-down on the
pin.
Figure 13 shows the typical connections between
the CS5460A and a serial EEPROM for proper au-
to-boot operation. In this mode, CS and SCLK are
driven outputs. SDO is always an output. During
the auto-boot sequence, the CS5460A drives CS
low, provides a clock output on SCLK, and drives
out-commands on SDO. It receives the EEPROM
data on SDI. The serial EEPROM must be pro-
grammed with the user-specified commands and
register data that will be used by the CS5460A to
change any of the default register values (if de-
sired) and begin conversions.
Figure 13 also shows the external connections that
would be made to a calibrator device, such as a PC
VD+
Mech. Counter
or
Stepper Motor
/EOUT
/EDIR
5 K
EEPROM
CS5460A
SCK
SCK
SDI
SO
SDO
SI
5 K
MODE
/CS
/CS
Connector to
Calibrator
Figure 13. Typical Interface of EEPROM to CS5460A
24
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