Digi BL1800 user manual Jackrabbit Function Calls, 1 I/O Drivers

4.4 Jackrabbit Function Calls

4.4.1 I/O Drivers

The Jackrabbit contains four high-power digital output channels, two D/A converter out- put channels, and one A/D converter input channel. These I/O channels can be accessed using the functions found in the JRIO.LIB library.

4.4.1.1 Initialization

The function jrioInit() must be called before any other function from the JRIO.LIB library. This function initializes the digital outputs and sets up the driver for the analog input/outputs. The digital outputs correspond to the Rabbit processor’s port E bits 0–3, and the analog I/O uses timer B; bits 1, 2, and 4 of port D; and bits 6 and 7 of port E.

The function void jrioInit() initializes the I/O drivers for Jackrabbit. In particular, it sets up parallel port D bits 1, 2, and 4 for analog output, port E bits 0–3 for digital output, and starts up the pulse-width modulation routines for the A/D and D/A channels. Note that these routines can consume up to 20% of the CPU’s processing power; the routines use timer B and the B1 and B2 match registers.

4.4.1.2 Digital Outputs

The Jackrabbit contains four high-power digital output drivers, HV0–HV3, on header J4. These can be turned on and off with the following functions from the library JRIO.LIB.

HV0, HV1, and HV2 are open-collector sinking outputs, and are able to sink up to 1 A (200 mA for the Jackrabbit and BL1820) from a 30 V source connected to the K line on header J4. HV3 is a sourcing output that is able to source up to 500 mA (100 mA for the BL1810 and BL1820) from a 30 V source connected to the K line.

CAUTION: Remember to cut the trace between K and Vcc inside the outline for header JP2 on the top side of the Prototyping Board if you are supplying K from a separate power supply. An exacto knife, a precision grinder tool, or a screwdriver may be used to cut through the traces as shown in Figure 16.

NOTE: Failure to do this could lead to

the destruction of the Rabbit 2000 microprocessor and other components once the Jackrabbit is connected to the Prototyping Board.

Cut gray trace as shown

Top Side

Prototyping

Board

JP2
		VCC	K
			Cut
	LS1				R3
	Buzzer				3
					2
COIL()-	R1				+
					1
		HV0	+RAWPOT PE4			GND AD0
	JP2				RT1
		BZR VCC	K	AD0	PD0

Figure 16. Cut Trace on Prototyping Board

When Vcc and K Are Different

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