User manual IROBOT COMMAND MODULE

[. . . ] iRobot Command Module ® Owners manual www. irobot. com Important Safety Instructions General saFeTY InsTruCTIOns · Read all safety and operating instructions before operating iRobot Command Module. · Retain the safety and operating instructions for future reference. · Follow all operating and use instructions. · Refer all non-routine servicing to iRobot. ePort saFeTY InsTruCTIOns The maximum voltage available on the ePor t is 21V, so the ePort pins will not shock you if they contact your skin. [. . . ] You can read the state of a pin whether it is an input or an output. The hexadecimal (hex) value 0xF8 = 11111000 in binary, so the most significant 5 pins (C3 ­ C7) become outputs. iRobot Command Module Owner's Manual 16 4. 9 using bitwise operators to selectively change bit values The C bitwise operators, bitwise-or (|=), bitwise-and (&=), and bitwise-exclusive-or (^=), as well as the not operator (~) should be used to change the value of one bit at a time with these registers. The following code sets pin B2 as an output: DDRB |= 0x04; 4. 10 Command module Internal Pins The Command Module's ePorts only expose pins B0-B3 and C0-C5. See the Hardware Reference in chapter 9 for the details and locations of these pins on the ports. The remaining pins are reserved for the Command Module's own hardware and the Create Cargo Bay Connector on the underside of the Command Module: Pin PB4 Description Serial port select. a0 = connect serial I/O to Create Create Power Detect. Serial Rx Serial Tx Create Device Detect Input. Change Create's baud rate to 19200 by toggling this pin 3 times with 200 ms pulses (or use the Baud command - see the Open Interface documentation) USB Detect Command Module Soft Button Command Module LED 1 Command Module LED 2 Create Power Toggle. Turn Create on or off with a low-to-high transition. Direction Output Input Input Output Output This sets the value of bit 2 to be 1, but doesn't affect the other bits in DDRB. The following code sets pin D7 as an input: DDRD &= ~0x80; PB5 PD0 PD1 PD2 This sets bit 7 in DDRB to be a 0 without affecting the other bits. Once you've set pin B2 as an output, the following code sets its state to high: PORTB |= 0x04; PD3 PD4 PD5 Input Input Output Output Output The following code sets pin B2 low: PORTB &= ~0x04; PD6 PD7 If you just want to flip the state of the pin (low to high or high to low), you can use the bitwise-exclusive-or operator. The following code flips the state of pin B2: PORTB ^= 0x04; To check whether a pin is high or low, read the PINx register and then use the bitwise-and operator to check only the associated bit. The following code branches your code according to the state of pin D7: if(PIND & 0x80) { /* if D7 is high, run this code */ } else { /* otherwise, if D7 is low, run this code */ } For these pins, only use the direction stated in the table above. The remaining pins (B6-7, C6-7) are for Command Module internal use only. Their direction is set in hardware and cannot be changed with software. If D7 was connected to a button, you could use this code to perform different actions depending on whether the button was being pushed. iRobot Command Module Owner's Manual 17 4. 11 adding a button and leD to the input example program In chapter 3, you saw that the input example program looks for button presses on Create and on the Command Module and plays a song and lights an LED when a button is pressed. The program is also looking for button presses on a top center ePort input pin and setting an ePort output pin to drive an LED. Buy a standard pushbutton and an LED from one of the sources listed in Appendix A. Solder them onto a male DB-9 connector as shown in Figure 4. The button is connected to pin 3 (B1) and pin 5 (GND), and the LED is connected to pin 2 (C1) and pin 4 (5V), with the flat side toward pin 2 and the longer lead connected to pin 4. This makes the LED active low (lit when low). leD Longer leg of LED Flat side of LED 4. 12 Taking an analog measurement using the aDC The I/O pins on PORTC of the Command Module can be used to take analog measurements with the processor's 10-bit Analog-to-Digital converter (ADC). For full details on the ADC, see the "Analog to Digital Converter" section of the processor datasheet, included on the Product CD. [. . . ] A low side driver is special type of output which can sink a large amount of current. Low side drivers are useful for controlling a motor or other power device as shown below. Each of the ePorts has three power connections: Vcc, Vpwr and Gnd. The ground line serves as digital and analog zero voltage reference. All of the specifications given in this booklet are referenced to the Gnd line. [. . . ]