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| | | PicPuter 2.0 : Chapter 1 : Hardware Requirements |
PicPuter really does not need much more than power and any oscilator to run. But in order to program PicPuter, you will need good serial port comunications. This requires an 18.432MHz crystal and an RS232 chip. But more on this later, first we need to select a microcontroller.
You can always just bypass this chapter and purchase a
PicPuter1 .
 1.01 : Selecting a Microcontroller |
PicPuter requires a rather specific microcontroller to operate. Microchip has released several new versions that will not function properly.
Works Chip Features
------ --------- ---------------------------
no PIC16F870 2K Program 64 bytes eeprom
no PIC16F871 2K Program 64 bytes eeprom
no PIC16F872 2K Program 0 bytes eeprom
V1.0 Only PIC16F873 4K program 128 bytes eeprom
V1.0 Only PIC16F874 4K program 128 bytes eeprom
yes PIC16F876 8K program 256 bytes eeprom but no ROBOT PORT
yes PIC16F877 8K program 256 bytes eeprom
no PIC16F876A 8K program 256 bytes eeprom (may work read/run only)
no PIC16F877A 8K program 256 bytes eeprom (may work read/run only)
no PIC16F876I 8K program 0 bytes eeprom
no PIC16F877I 8K program 0 bytes eeprom
If a different chip is required then PicPuter is not for you. You will also be giving up an easy interface an __LCD__ display, 5 __ADC__ channels 2 stepper motor and 4 pulse width modulators, as well as an assembler and __HEXRECS__ support.
| 1.02 : Power Ground and Reset |
PicPuter requires a single supply voltage from 4.5V to 5.5V. VDD should be hooked up the positive supply voltage, while VSS needs to be hooked up to ground.
RC0 or PORTC.0 needs to be connected through a 10K resitor to +5V.
This pin is sampled at reset to determin if basic should run (Pin HI) or if the fail safe
bootloader should run (Pin LOW). This pin is also used to generate the RS232 CTS signal.
Note: RA4 or PORTA.4 must also be grounded if the RS232 RTS signal is not used.
MCLR should be connected to connected though a 10K resitor to +5V, but the internal pull-up resistor should be enough. Grounding this pin resets PicPuter.
| 1.03 : Oscillator |
By default, PicPuter requires an 18.432MHz crystal to opperate the serial port . This value was carefully choosen two divide by various baud rates and the real time clock.
PicPuter will function at any frequency, its just that that running a 115.2K baud serial port reliably requires good timing. If a 20MHz crystal is used, a baud rate of 19.2K baud is possible with a 0.3% error.
| 1.04 : RS232 |
Hooking up an RS232 port requires at least 2 lines, RX and TX. They are on PortC.6 and PortC.7.
Since PicPuter implements hardware flow control, PortA.4 must be grounded in 2 wire mode.
A more robust serial port uses 4 wires. The signals are TX, RX, RTS, CTS. They are on PortC.6, PortC.7, PortA.4, and PortC.0
| 1.05 : Optional |
All other pins are optional, they may be hook up optional devices such as an __LCD__,
stepper motor , __SERVO__, or used for general purpose IO.
| 1.06 : Programing the Microcontroller |
There are many ways to program the microcontroller, but you need to make sure that the data eeprom is written as well as the program memory. The eeprom contains the license key that enables PicPuter to work. The default evaluation license key is contained in the hex file, but you may need to enable an option on the programming software to ensure that the data is written. If the eeprom is left blank, or is somehow modified, PicPuter will not boot.
[ index | memory |
math | statements | variables | registers | assembler ]
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