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LHO 13

The 8051CF020 and the University Daughter Card

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Resources

• https://www.silabs.com/Support%20Documents/TechnicalDocs/C8051F02x.pdf

• University Daughter Card User Manual

• Embedded_Programming_Textbook.zip

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Peak throughput 25 MIPS

FLASH program memory 64 K

On-chip data RAM 4352 bytes

Full-duplex UARTS x 2

16-bit timers x 5

Digital I/O ports 64-pin

12-bit 100 ksps ADC 8 channels

8-bit 500 ksps ADC 8 channels

DAC resolution 12-bit

DAC outputs x 2

Analog comparators x 2

Interrupts 2 levels

PCA (programmable counter arrays) 5 channels

Internal oscillator 25 Mhz

Debug circuitry

4Standard 8051

5C8051F020

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I/O Ports• Ports 0, 1, 2 and 3 are bit- and byte-addressable• Four additional ports (4, 5, 6 and 7) are byte-addressable

only• There are a total of 64 general purpose port I/O pins• Access to the ports is possible through reading and

writing the corresponding port data registers (P0, P1, etc.)

• All port pins are 5 V tolerant and support configurable input/output modes and weak pull-ups

• In addition, the pins on Port 1 can be used as analog inputs to ADC1

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The Digital Crossbar• The digital crossbar is

essentially a large digital switching network that allows mapping of internal digital peripherals to the pins on Ports 0 to 3

• This is achieved by configuring the crossbar control registers XBR0, XBR1 and XBR2

• Allows the system designer to select the exact mix of GPIO and digital resources needed for the particular application

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12-Bit Analog-to-Digital Converter (ADC0)

• On-chip 12-bit successive approximation register (SAR) analog-to-digital converter (ADC0)

• 9-channel input multiplexer and programmable gain amplifier

• The ADC is configured via its associated special function registers

• One input channel is tied to an internal temperature sensor, while the other 8 channels are available externally

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8-Bit Analog-to-Digital Converter (ADC1)• On-board 8-bit SAR analog-to-digital converter (ADC1)• Port 1 can be configured for analog input• 8-channel input multiplexer and programmable gain amplifier• The ADC is configurable via its configuration SFRs

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Digital-to-Analog Converters

• Two 12-bit digital-to- analog converters: DAC0 and DAC1

• The DAC voltage reference is supplied via the dedicated VREFD input pin

• The DACs are especially useful as references for the comparators

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Comparators

• There are two analog comparators on chip: CP0 and CP1

• The comparators have software programmable hysteresis

• Generate an interrupt on its rising edge, falling edge or both

• The comparators' output state can also be polled in software and programmed to appear on the lower port I/O pins via the crossbar

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Voltage Reference for ADC and DAC • A voltage reference has to be

used when operating the ADC and DAC

• Three external voltage reference input pins: VREF0, VREF1 and VREFD

• ADC0 may also reference the DAC0 output internally

• ADC1 may also reference the analog power supply voltage (AV+)

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Internal Voltage Reference Generator

• The internal voltage reference circuit consists of a 1.2 V band-gap voltage reference generator and a gain-of-two output buffer amplifier (2.4 V output)

• The internal reference may be routed via the VREF pin to external system components or to the voltage reference input pins

• The reference control register, REF0CN, enables/disables the internal reference generator and selects the reference inputs for ADC0 and ADC1

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ToolStick UniDC Hardware Overview

I/O PinsP0[7..2], P1, P2

PotentiometerLinear output that sweeps from 0V to 3.3V

Target MCU C8051F020

Power LEDIndicates

3.3V is available

Reset Switch

Analog I/O Pins

Push-button SwitchesP5[3..0]

LEDsP5[7..4]

DIP Switches P4

Crystal22.1184 MHz

Prototype Area

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Handling The ToolStick

• Caution: The modular ToolStick components are not encased in plastic. This makes both the base adapter (BA) and the daughter cards (DC) susceptible to electrostatic discharge (ESD) damage.

• Follow these recommendations to protect the hardware– Never connect or disconnect a ToolStick daughter card from the base adapter

while connected to a PC

– Always connect or disconnect a ToolStick by holding the large plastic connector or the edges of the boards

– Be careful when using the mechanical components, such as the potentiometers, so as to not stress the connectors

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Handling The ToolStick

The Wrong way to hold the ToolStick

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Handling The ToolStick

The Correct way to hold the ToolStick

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Consider a simple program#include <c8051f020.h> // SFR declarationsextern void Init(void); // in udc_init,cextern void wr_leds(unsigned char); // in unc_init.cextern unsigned char rd_buttons(void); // in unc_init.cvoid main (void){ Init(); // call to external function initialize UDC while(1) { wr_leds(rd_buttons()); // call external functions }}

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//udc_init.c - version 1.0#include <c8051f020.h> // SFR declarations//----------------------------------------------------// Init - Configure UDC// Returns : None// Parameters : None//-----------------------------------------------------void Ext_Osc_Init(void); // switch clock to XTALvoid init_crossbar(void);void init_ports(void);

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void Init (void){// Disable interrupts EA = 0;// Disable watchdog timer WDTCN = 0xde; WDTCN = 0xad;// Enable crossbar switch init_crossbar();// Set up ports init_ports(); Ext_Osc_Init(); // Use external XTAL}

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//-----------------------------------------------------------------------------// Init_crosbar - Configure crossbar switch// Returns : None// Parameters : None//-----------------------------------------------------------------------------void init_crossbar (void){ XBR0 = 0x04; // Enable UART 0 TX to P0.0, RX to P0.1 XBR1 = 0x80; // Output system clock to P0.2 P74OUT = 0x08; // Set P5(7_4) to push pull output XBR2 = 0x40; // Enable cross bar}

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XBR2 = 0x40; // Enable cross bar

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XBR0 = 0x04; // Enable UART 0 TX to P0.0, RX to P0.1

30XBR1 = 0x80; // Output system clock to P0.2

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P74OUT = 0x08; // Set P5(7_4) to push pull output

32XBR2 = 0x40; // Enable cross bar

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void init_ports(void){ P0MDOUT = 0x04; //Set P0.2 (sys clk) to push pull for fast rise time P1MDOUT = 0x00; P2MDOUT = 0xFF; //Set P2 to push pull for fast rise times P3MDOUT = 0x00; P5 = 0x0f; //TURN ON LEDS}

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unsigned char rd_buttons(void){ unsigned char btns; btns = (~P5) & 0x0f; return(btns);}

void wr_leds(unsigned char leds){ P5 = (leds << 4) | 0x0f;}