The C Programmer’s Guide to the QVGA Controller

High resolution transparent analog touchscreen with software controlled beeper for audible feedback. Custom antiglare, clear, and EMI touchscreens are also available.

Communications

A hardware UART supports either RS232 or RS485 at up to 19.2 Kbaud.

A second software UART implements RS232 at up to 4800 baud.

A fast synchronous serial peripheral interface (SPI) provides communications at speeds up to 2 megabaud.

High Current Drivers

Four open-drain MOSFET drivers can sink up to 150 mA continuously, or up to 1 amp intermittently. Onboard snubber diodes allow control of inductive loads.

Power

Your QVGA Controller includes a high-efficiency switching regulator with surge suppression, transient filtering, and EMI/RFI filtering to provide clean supplies for the onboard analog and digital electronics. You need only supply regulated or unregulated DC power in the range of 8 to 26 volts if using a monochrome display, or 15 to 26 volts if using an EL display.

Surge Suppression

The raw input is protected by a “varistor” rated at 33 Volts DC. This metal oxide surge suppresser protects the QVGA Controller by clamping high voltage spikes before they have a chance to do any harm. The varistor has no effect if the input voltage is less than the maximum specified, or 26 volts. Above 33 volts the device starts to conduct current, and it acts like a short circuit to high voltages, thus clamping the voltage spikes. To prevent this varistor from consuming current, you should make sure that the maximum DC voltage supplied is always less than 26 volts.

EMI/RFI Filter

Additional protection is provided by an electro-magnetic interference (EMI) and radio frequency interference (RFI) filter that prevents high frequency noise from invading the circuitry via the power input, and also prevents EMI from propagating back to the external power supply. The EMI filter is implemented by a two stage PI network of inductors and capacitors. The output of the first stage filter, called V+raw, is passed to the Wildcard module bus for supply to Wildcard modules that require their own unregulated DC power. This unregulated voltage is free of high-frequency and high-voltage transients. If you design custom add-on Wildcard boards, we recommend that you use V+raw as the input for local 5 Volt regulators. It is good design practice to place local voltage regulators on each board, as this minimizes noise problems and improves modularity.

The QVGA Controller board is designed for reliable low noise operation. It is implemented as a state of the art 6-layer surface-mount board. Two inner layers are dedicated ground and power planes, providing low-impedance return paths for digital current spikes.

Parameter	Min	Typ.	Max	Units	Conditions
Input Voltage – Monochrome Display	8		26	Volts
Input Voltage – EL Display	15		26	Volts
Power Usage – Monochrome Display		5	6	Watts	No Wildcards
Power Usage – EL Display		12	20	Watts	No Wildcards
Power Usage – per Wildcard		0.5			Each Wildcard

Operating Conditions

Parameter	Min	Max	Units	Conditions
Operating Temperature Range – Electronics	0	70	°C	Industrial Temp also available (-40 to 85°C)
Operating Temperature Range – Monochrome Display	-20	60	°C
Storage Temperature Range – Monochrome Display	-20	70
Temperature Range – EL Display	-25	65	°C
Humidity	0	95	% Relative Humidity	At 0 to 45°C, no condensation
Humidity	0	85	% Relative Humidity	At 50°C, limited by the monochrome display. At other temperatures the absolute humidity must be less than that provided by 85% RH at 50°C, or 100% at 47°C.

Memory

Parameter	Standard	With Option	Units
Flash	384	768	KBytes
RAM	257	641	KBytes
EEPROM	512		Bytes
Battery-Backed RAM	128		KBytes
Battery-Backed Real-Time Clock
Compact Flash Wildcard		64-256	MBytes

CPU I/O (CPU Ports A, D, E)

Parameter	Min	Max	Units	Conditions
I/O Voltage Range	-0.1	5.3	Volts
Input Low Voltage		1.0	Volts	0.2 x V_DD
Input High Voltage	3.5		Volts	0.7 x V_DD
Input Leakage Current		±1	mA
Output Low Voltage		0.4	Volts	at 1.6 mA
Output High Voltage	3.7		Volts	at –0.8 mA and V_DD=4.5 V
Output Source		25	mA	<65 W output drive impedance, one pin at a time, observing max power dissipation limits.
Output Sink		25	mA	<65 W output drive impedance, one pin at a time, observing max power dissipation limits.
Note: We recommend limiting total package power dissipation accruing from I/O current to 800 mW or less, to assure that the junction temperature remains below 125ºC.

PIA I/O (Ports PPA, PPB, PPC)

Parameter	Min	Max	Units	Conditions
I/O Voltage Range	-0.5	5.5	Volts
Input Low Voltage		0.8	Volts	Inputs latch high or low. With an input high, the input pin will source up to 350 mA. An external device must sink this current to pull the input low. Under worst-case conditions, 2 Kohms or less to ground will always pull an input low. Latched low, the input will sink up to 350 mA before it can be pulled high. Under worst case conditions, 5 Kohms or less to a 5V supply will always pull the input high. PPA contains both “pull-up” and “pull-down” bus hold, PPB and PPC pull-up only.
Input High Voltage	2.0		Volts
Input Leakage Current	-1.0	1.0	mA
Bus Hold Current	± 50	± 350	mA
Output Low Voltage		0.4	Volts	at 2.5 mA
Output High Voltage	3.0 V_cc –0.4		Volts	I_OH= –2.5 mA worst case, –20 mA typical I_OH= –100mA
Output Source	-2.5	-4	mA	±2.5 ma. guaranteed to 1.7 V through 500 ohms. -4 ma. at V_OH=3.0 V. The max current must be limited by external circuitry.
Output Sink	2.5	4	mA	4 ma. at V_OL=0.4 V. The max current must be limited by external circuitry.
Power Dissipation		1	W
Note: We find that these pins easily provide up to ±20 ma. at their V_OH and V_OL. The 4 ma. in the data sheet may be based on a max package power dissipation assuming that all 24 outputs are driven simultaneously.

8-Bit Digital to Analog Conversion

Parameter	Min	Typical	Max	Units	Conditions
Number of Output Channels		8
Update Rate			25,000	Samples per second
Full-Scale Output Range	0		3	Volts
Settling Time		3.5		ms
Slew Rate		4		Volts / ms
Integral Nonlinearity		0.5		LSB
Differential Nonlinearity			1	LSB
Load Drive Capability			1	kW	In parallel with 20pF

8-bit Analog To Digital Conversion

Parameter	Min	Typical	Max	Units	Conditions
Number of Input Channels		8
Sampling Frequency			100,000	Samples per second
Input Voltage Range	-0.1	0.0 to 5.0	5.1	Volts
Nonlinearity			1	LSB
Absolute Accuracy			2	LSB

12-bit Analog To Digital Conversion

Parameter	Min	Typical	Max	Units	Conditions
Number of Input Channels	4		8		4 differential or 8 single ended
Sampling Frequency			30,000	Samples per second
Input Voltage Range	-5.3	-5.0 to 5.0	5.3	Volts
Nonlinearity			0.5	LSB
Input Noise		200		mV
Effective Resolution		11.9		Bits

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The C Programmer’s Guide to the QVGA Controller

Table of Contents

Appendix A: QVGA Electrical Specifications

General Specifications

CPU

Timers

Interrupts

Runtime Security

Touchscreen/Display User Interface