Chameleon-PIC Nurve Networks, Chameleon-PIC Datasheet - Page 243

• Manufacturer Part Number: Chameleon-PIC
• Description: MCU, MPU & DSP Development Tools PIC24 & PROPELLER DEV SYSTEM (SBC)
• Manufacturer: Nurve Networks

Specifications of Chameleon-PIC

• Processor To Be Evaluated: PIC24
• Data Bus Width: 16 bit
• Interface Type: USB, VGA, PS/2, I2C, ISP, SPI
• Operating Supply Voltage: 3.3 V, 5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Referring to the figure, the client/master processor issues commands over the SPI interface which the master control
program running on the Propeller chip, processes in a large message dispatching loop to the proper driver object. Thus, to
add messages or functionality we have to consider the following things:
1. Will the Propeller driver need another object or driver? If so, we need to add this and then add code to the main
message dispatcher loop that passes messages from the client to the new Propeller object.
2. If we add messages to the system, we need to make sure they are unique and don’t overlap any other messages. Its
good practice to not use message ids we have already used since you want to be as compatible as possible. Both the
Propeller driver cham_default2_drv_112.spin and cham_pic_i2c_spi_drv_v010.h contain the master message id lists
(copies) and the various library API files have functions that wrap the use of the messages in higher level functions.
3. There are three classes of messages we can add;

Class 1: (Same object more functionality). There is already a driver for the messages, the driver supports some
extra functionality that we haven’t exposed yet and wish to. The sound driver for example falls under this
category. I barely exposed its true power, so you might want to add more messages. In this case, you have to add
Figure 33.1 – The flow of messages from the PIC (or AVR) to the Propeller.
© 2009 NURVE NETWORKS LLC “Exploring the Chameleon PIC 16-Bit”
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