PDALib.py - Pi Droid Alpha Python Library Discussion

[alanmcdonley]

Copied from http://forums.mikronauts.com/viewtopic.php?p=155#p155 to start a new thread title.

I've uploaded PDALib.py v0.90 to the Pi Droid Alpha product page

http://www.mikronauts.com/raspberry-pi/pi-droid-alpha/

After downloading, rename file as PDALib.py

[alanmcdonley]

Topic: Driving motor 1 and motor 2 (basic)

Is this correct? (edited: pinMode() was improperly setMode() )

Code: Select all

import PDALib
import time

PDALib.pinMode(6,PDALib.PWM)  # init motor1 speed control pin
PDALib.pinMode(7,PDALib.PWM)  # init motor2 speed control pin

PDALib.pinMode(12,PDALib.OUTPUT)  #init motor1 dirA/Fwd    enable
PDALib.pinMode(13,PDALib.OUTPUT)  #init motor1 dirB/Bkwd  enable
PDALib.pinMode(14,PDALib.OUTPUT)  #init motor2 dirA/Fwd    enable
PDALib.pinMode(15,PDALib.OUTPUT)  #init motor2 dirB/Bkwd  enable

# init all direction pins to off
PDALib.digitalWrite(12,0)  #set to off/coast
PDALib.digitalWrite(13,0)  #set to off/coast
PDALib.digitalWrite(14,0)  #set to off/coast
PDALib.digitalWrite(15,0)  #set to off/coast

# get ready to go forward
PDALib.digitalWrite(12,1)  #set to forward
PDALib.digitalWrite(14,1)  #set to forward

# setting speed will start us going  (zero to fast in one command for this test)
PDALib.analogWrite(6,127)  #set motor1 to half speed
PDALib.analogWrite(7,127)  #set motor2 to half speed

time.sleep(10.0)  # drive while asleep at the wheel for 10 seconds
                           # (bad idea but this is a test)

# two ways to stop - set speed to 0 or set direction to off/coast
PDALib.digitalWrite(12,0)  #set to off/coast to stop
PDALib.digitalWrite(14,0)  #set to off/coast to stop

# turn off the speed pin - not needed when dir pins are off, but good idea
PDALib.analogWrite(6,0)  #set motor1 to zero speed
PDALib.analogWrite(7,0)  #set motor2 to zero speed



[mikronauts]

Yes - that looks correct.

Generally, I set he direction separately, then just use analogWrite() to control the speed - and break by analogWrite(0), as it requires less code

FYI, I expect to release the initial manual in a few days.

[alanmcdonley]

In PDALib.py there is a line:

spi.xfer([0x40,0xff,0xff]) # sets all pins as inputs

should this be?

spi.xfer([0x40,DIO_DIR,0xff,0xff]) # sets all pins as inputs

# 0x40 = write opcode with hardware address zero (0100AAAW W=0 for write)
# DIO_DIR = 0 = IODIRA register
# 0xff = IODIRA value - 1= input, 0xFF =all input direction
# 0xff = IODIRB value (auto register address incrementing on by default)

[mikronauts]

You are correct!

Thank you for the help in debugging the library.

I got my internet back a couple of hours ago!!!