Microchip Technology DM300024 Hoja De Datos
dsPICDEM™ 1.1 Plus Development Board User’s Guide
DS70099D-page 36
©
2006 Microchip Technology Inc.
• Data Converter Interface – Interfaced to an external Si3000 voice band Codec for
transmission of DTMF PCM signals
• INTx pins – Used for detecting switch SW1-SW4 inputs
• Hierarchical/Prioritized Interrupt Control with nesting enabled
3.4
DATA AND CONTROL FLOW
3.4.1
Power-up Sequence
The power-up peripheral initialization sequence is shown in Table 3-3.
TABLE 3-3:
POWER-UP PERIPHERAL INITIALIZATION SEQUENCE
Seq
Module or Function
Initialization Process
1
Timer1
Configured to count to 125 µS, but not enabled.
2
Timer2
Configured to count to 1 second using a 256:1 prescaler
setting.
setting.
3
Timer3
Configured to count up to 1.14 seconds using the 256:1
prescaler setting.
prescaler setting.
4
Timer4 and Timer5
Configured to operate in the 32-bit Timer mode, but not
enabled until needed.
enabled until needed.
5
Interrupt Service
Routine (ISR)
Routine (ISR)
Processing is enabled for Timer2 and Timer3.
6
UART2
Both the transmitter and receiver are configured for
interrupt-driven operation at 57600 baud.
interrupt-driven operation at 57600 baud.
7
SPI 2
Initially configured to operate in an interrupt-driven mode at
F
F
CY
/8 Hz (where F
CY
= 7.3728 MHz). The module communi-
cates at F
CY
/8 Hz in 8-bit mode while displaying results on the
LCD controller. When it is used to step the MCP41010, it
operates in the 16-bit mode at F
operates in the 16-bit mode at F
CY
/32 Hz.
8
Data Converter
Interface (DCI)
Interface (DCI)
Configured for Master mode. Initially configured to use two of
four buffers. Transmits/receives in time slot 1 at the frame rate
of 7200 Hz for configuring the Si3000 external voice band
Codec.
four buffers. Transmits/receives in time slot 1 at the frame rate
of 7200 Hz for configuring the Si3000 external voice band
Codec.
9
Si3000
Configured for Slave mode. The Si3000 line and speaker
ports are enabled. Signal attenuation is set to 0 dB. The ADC
input from the Si3000 is attenuated by 34.5 dB and is not used
in this demo.
ports are enabled. Signal attenuation is set to 0 dB. The ADC
input from the Si3000 is attenuated by 34.5 dB and is not used
in this demo.
10
DCI
Re-initialized to operate with all four buffers in interrupt-driven
mode for transmitting DTMF PCM words to the Si3000 Codec.
mode for transmitting DTMF PCM words to the Si3000 Codec.
11
External interrupt
pins INT1-INT4
pins INT1-INT4
Configured to interrupt on the falling edge and used for
switches SW1-SW4, respectively.
switches SW1-SW4, respectively.
12
12-bit ADC
Configured to operate at 16000 Hz sampling rate and gener-
ate an interrupt every 16 sample-convert sequences. The
ADC samples channel AN3 (sine wave), AN4 (RP2), AN5
(RP3), AN6 (RP1) and AN8 (temperature sensor U9).
ate an interrupt every 16 sample-convert sequences. The
ADC samples channel AN3 (sine wave), AN4 (RP2), AN5
(RP3), AN6 (RP1) and AN8 (temperature sensor U9).
13
Interrupts
Peripheral interrupts are configured. Nested interrupts are
enabled.
enabled.