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LHO 13
The 8051CF020 and the University
Daughter Card
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Resources
• https://www.silabs.com/Support%20Docum
ents/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
x2
16-bit timers
x5
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
x2
Analog comparators
x2
Interrupts
2 levels
PCA (programmable counter arrays)
5 channels
Internal oscillator
25 Mhz
Debug circuitry
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Standard 8051
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C8051F020
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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-todigital 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-toanalog 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
DIP Switches
Push-button Switches
LEDs
Power LED
Indicates
3.3V is
available
P4
P5[7..4]
P5[3..0]
Prototype Area
Reset
Switch
I/O Pins
P0[7..2], P1, P2
Target MCU
C8051F020
Analog
I/O Pins
Crystal
22.1184 MHz
Potentiometer
Linear output that sweeps from 0V to 3.3V
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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 declarations
extern void Init(void);
// in udc_init,c
extern void wr_leds(unsigned char); // in unc_init.c
extern unsigned char rd_buttons(void); // in unc_init.c
void 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 XTAL
void 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
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XBR1 = 0x80; // Output system clock to P0.2
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P74OUT = 0x08; // Set P5(7_4) to push pull output
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XBR2 = 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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void wr_leds(unsigned char leds)
{
P5 = (leds << 4) | 0x0f;
}
unsigned char rd_buttons(void)
{
unsigned char btns;
btns = (~P5) & 0x0f;
return(btns);
}
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