MSP53C691 Device Initialization
2-7
MSP53C691 Hardware Description
2.5
MSP53C691 Device Initialization
The RESET pin is configured as an external interrupt (see Figure 2–5). It
provides the means for hardware initialization of the device. When the RESET
pin is held low, the device assumes a deep sleep state and various registers
are initialized. After the RESET pin is taken high, the device gets initialized and
pulls INRDY low when the slave is ready to receive the oscillator selection
command (see the
Software Description chapter for a description of the
oscillator selection command). The oscillator selection command (0xB) is sent
through the DATA0–3 line while setting the DATA4 line low (indicating that it
is a command). When the slave receives the oscillator selection command
(0xB), it pulls INRDY low again to request the parameter (0x1 or 0x2) for the
command. After the parameter is received by the slave, it goes through the rest
of the initialization process and pulls INRDY low when the oscillator is
stabilized and the slave is ready to receive data/command.
Note:
If the slave does not receive the oscillator selection command as the first
command when INRDY goes low for the first time, or if the slave does not
receive the subsequent parameters for the oscillator control command (0x1
or 0x2), the slave resets itself again.
Figure 2–5. MSP53C691 RESET Diagram
MSP53C691
RESET
1 k
Ω
100 k
Ω
1
µ
F
V
DD
The MSP53C691 is considered to be properly initialized after the following
events take place:
1) The microcontroller sets RESET low.
2) The microcontroller sets STROBE high throughout the initialization pro-
cess.
3) The microcontroller sets RESET high.
4) The microcontroller waits for INRDY to go low.
5) The microcontroller sets R/W low.
6) The microcontroller puts 0xB (oscillator control command) on the data-bus
(DATA0–3) and sets the DATA4 (DATA/COMMAND) line low.
7) The microcontroller pulls STROBE low, waits for a minimum of 300 ns,
then pulls STROBE high again.
Содержание MSP53C691
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