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C8051F930-DK

22

Rev. 0.5

6.

What can I do to reduce active supply current?

Below are some suggestions for reducing the active supply current:

 

a.  Clear all wake-up sources in the PCU0CF register. This will allow the low power oscillator to be disabled 

when it is not being used as the system clock. This optimization can reduce the supply current by up to 
30 µA.

b.  When operating at system clock frequencies above 10 MHz, minimize supply current by setting the 

BYPASS bit (FLSCL.6) to 1. If the system clock needs to decrease below 10 MHz, clear the BYPASS bit 
to 0.

c.  If the precision oscillator is not being used, turn off the precision oscillator bias by setting the OSCBIAS 

bit (REG0CN.4) to 0.

7.

Why does P0.7/IREF0 have a voltage of 200 mV when IREF0CN is set to 0x00?

When IREF0CN is set to 0x00, the current reference is completely turned off. When a shorting block is installed 
on J7, the voltage at P0.7/IREF0 should be 0 V unless one of the following conditions is present:

a.  The P0.7/IREF0 pin is not configured for analog I/O (weak pull-up enabled).
b.  The P0.7/IREF0 pin is being used as CTS (a shorting block is installed on J12).

8. I have configured a Port pin as an analog input. Why is it still shorted to ground? 

On C8051F93x-C8051F92x devices, configuring a Port pin to analog mode (using PnMDIN) disables the digital 
input path and the weak pull-up. It does not explicitly disable the output drivers. 

Software can ensure that the output drivers are disabled by configuring the Port pin to open-drain output mode 
(using PnMDOUT) and writing 1 to the port latch. 

9.

Why does power consumption increase when an analog signal (hovering around mid-supply) is 
connected to a digital input?

This phenomenon is called the “crowbar” effect and is present in all CMOS circuitry. If the input of a CMOS 
structure is not a strong 1 or 0, then both the PMOS and NMOS devices are partially turned on causing current 
flow from VDD to GND. 

To prevent the “crowbar” effect, ensure that pins with analog voltage levels are configured for analog I/O. 

10.

Why does the dc/dc converter stop regulating when the load current exceeds 10 mA?

The default register settings for the dc/dc converter are optimized for low power applications requiring less than 
10 mA of supply current. If the application requires additional supply current, the default values may be 
overridden to provide up to 65 mW of output power.

To configure the dc/dc converter to high power mode, perform the following steps prior to enabling any high 
power device:

a.  Set DC0CN = 0x01. This selects the high-current switches.
b.  Set DC0CF = 0x04. This sets the peak inductor current limit to 500 mA.

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Summary of Contents for C8051F930-DK

Page 1: ...he C8051F93x C8051F92x data sheet for the differences between the members of this MCU family 2 Kit Contents The C8051F930 Development Kit contains the following items C8051F930 Target Board C8051Fxxx Development Kit Quick Start Guide Silicon Laboratories IDE and Product Information CD ROM CD content includes the following Silicon Laboratories Integrated Development Environment IDE Keil 8051 Develo...

Page 2: ...ation The default directory is C SiLabs MCU CP210x 2 The final window will give an option to install the driver on the target system Select the Launch the CP210x VCP Driver Installer option if you are ready to install the driver 3 If selected the driver installer will now launch providing an option to specify the driver installation location After pressing the Install button the installer will sea...

Page 3: ...nd linker place no restrictions on code size 3 4 2 Keil Evaluation C51 C Compiler The evaluation version of the C51 compiler is the same as the full version with the following limitations 1 Maximum 4 kB code generation 2 There is no floating point library included When installed from the CD ROM the C51 compiler is initially limited to a code size of 2 kB and programs start at code address 0x0800 R...

Page 4: ...matically generating initialization source code to configure and enable the on chip resources needed by most design projects In just a few steps the wizard creates complete startup code for a specific Silicon Laboratories MCU The program is configurable to provide the output in C or assembly language For more information refer to the Configuration Wizard documentation Documentation and software is...

Page 5: ...s battery profiles for common battery types such as AAA AA A76 Button Cell and CR2032 coin cell The discharge profile is application specific and describes the supply current requirements of the system under various supply voltages and battery configurations The discharge profile is independent of the selected power source Several read only discharge profiles for common applications are included i...

Page 6: ...ly current The V2 and V1 voltages at the top of the two columns specify the voltages at which the current measurements were taken The Battery Life Estimator creates a linear approximation based on the input data and is able to feed the simulation engine with an approximate supply current demand for every input voltage The minimum system operating voltage input field allows the system operating tim...

Page 7: ...one single cell battery two single cell batteries in series and two single cell batteries in parallel Figure 5 shows the simulation output window Figure 5 Battery Life Estimator Utility Simulation Results Form The primary outputs of the Battery Life Estimator are an estimated system operating time and a simulated graph of battery voltage vs time Additional outputs include estimated battery capacit...

Page 8: ... cable 2 Connect one end of the USB cable to the USB connector on the USB Debug Adapter 3 Verify that a shorting block is installed on J17 and that SW5 is in the ON position 4 Connect the other end of the USB cable to a USB Port on the PC 5 Connect the ac dc power adapter to power jack P1 on the target board Optional Notes Use the Reset button in the IDE to reset the target when connected using a ...

Page 9: ...uild a program and download it to the target in preparation for debugging The IDE will automatically create a single file project using the currently open and active source file if you select Build Make Project before a project is defined 5 1 Creating a New Project 1 Select Project New Project to open a new project and reset all configuration settings to default 2 Select File New File to open an e...

Page 10: ... section Next the correct Debug Interface must be selected C8051F93x C8051F92x family devices use the Silicon Labs 2 wire C2 debug interface Once all the selections are made click the OK button to close the window 3 Click the Connect button in the toolbar or select Debug Connect from the menu to connect to the device 4 Download the project to the target by clicking the Download Code button in the ...

Page 11: ...ftware 8051 tools Therefore when using the Keil 8051 tools included with the development kit A51 C51 it is not necessary to copy a register definition file to each project s file directory 6 2 Blinking LED Example The example source files F93x_Blinky asm and F93x_Blinky c installed in the default directory SiLabs MCU Examples C8051F93x_92x Blinky show examples of several basic C8051F930 functions ...

Page 12: ...J10 J11 Selects the power supply source Wall Power AAA Battery or Coin Cell J12 Connects Port I O to UART0 interface J13 Connects external VREF capacitor to the P0 0 VREF J14 Connects the PCB ground plane to P0 1 AGND J15 Connects negative potentiometer R14 terminal to pin P1 4 or to GND J16 Connects the potentiometer R14 wiper to P0 6 CNVSTR J17 Creates an open in the power supply path to allow s...

Page 13: ...l mode BT2 Battery Holder for 1 5 V AAA Use for two cell mode only BT3 Battery Holder for 3 V Coin Cell CR2032 BT4 Battery Holder for 1 5 V Button Cell A76 or 357 Figure 8 Bottom of C8051F930 Target Board NEG POS NEG POS BT4 BT2 BT1 BT3 CR2032 A76 or 357 AAA AAA Note BT2 is only used in two cell mode Downloaded from Elcodis com electronic components distributor ...

Page 14: ...ng Blocks Factory Defaults P0 2 P0 3 Pin 1 Pin 2 J3 J4 J2 P3 CP 2103 U3 P2 DEBUG J9 USB POWER RESET P1 6 P1 5 POWER OFF BEFORE SW4 SWITCHING MODE 2 CELL 1 CELL J17 IMEASURE H2 SILICON LABS www silabs com H1 Pin 1 J6 VDD DC J5 J7 J13 F930 U1 J14 J11 J10 VBAT WALL_PWR AAA_BAT COIN_CELL TOUCH SENSE SWITCH P2 0 TOUCH SENSE SWITCH P2 1 P1 4 J15 GND J16 R15 J12 J8 3VD 1VD VBAT J1 SW5 ON OFF P1 SW2 SW3 P...

Page 15: ...es 3 VD and passes it through a 1 65 V LDO The LDO s output voltage is variable and can be set by changing the value of resistor R32 7 2 2 AAA Battery When the J10 J11 three way header is set to AAA_BAT the C8051F930 Target Board may be powered from a single AAA battery inserted in BT1 or from the series combination of the AAA batteries inserted in BT1 and BT2 A single battery is selected when SW4...

Page 16: ...nal crystal may be used Refer to the C8051F93x C8051F92x data sheet for more information on configuring the system clock source 7 3 2 External Oscillator Options The target board is designed to facilitate the installation of an external crystal Y1 Install a 10 M resistor at R9 and install capacitors at C20 and C21 using values appropriate for the crystal you select If you wish to operate the exter...

Page 17: ...o the USB connector P3 One power LED is also added to each of the two primary supply nets powering the MCU VDD DC and VBAT The LEDs connected to the supply nets may be disabled by removing the shorting blocks from J1 and J5 Two LEDs are connected to GPIO pins P1 5 and P1 6 for use by application software See Table 1 for the port pins and headers corresponding to each LED A potentiometer R15 is als...

Page 18: ... 6 nc 7 nc 7 nc 7 nc 8 nc 8 nc 8 nc 9 nc 9 nc 9 nc 10 nc 10 P0 7 IREF0 10 P0 6 CNVSTR 11 P0 5 RX 11 P0 4 TX 11 P0 3H 12 P0 2H 12 P0 1 AGND 12 P0 0 VREF 13 P1 7 AD7 13 P1 6 AD6 13 P1 5 AD5 14 P1 4 AD4 14 P1 3 AD3 14 P1 2 AD2 15 P1 1 AD1 15 P1 0 AD0 15 A7 Latch 16 A6 Latch 16 A5 Latch 16 A4 Latch 17 A3 Latch 17 A2 Latch 17 A1 Latch 18 A0 Latch 18 P2 3 A11 18 nc 19 nc 19 nc 19 P2 3 A11 20 P2 2 A10 20...

Page 19: ...lock positions for connecting each of these signals to the CP2103 are listed in Table 4 To use this interface the USB to UART device drivers should be installed as described in Section 3 2 CP210x USB to UART VCP Driver Installation on page 2 7 9 Analog I O H1 Several of the C8051F930 target device s port pins are connected to the H1 terminal block Refer to Table 5 for the H1 terminal block connect...

Page 20: ... 0 VREF when a shorting block is installed on J13 Using the Precision Voltage Reference is optional since F93x F92x devices have an on chip High Speed Voltage Reference The shorting block J14 allows P0 1 AGND to be connected to ground This provides a noise free ground reference to the analog to digital Converter The use of this dedicated analog ground is optional 7 12 C2 Pin Sharing On the C8051F9...

Page 21: ... is under software control be sure to set P1 4 to logic HIGH prior to placing the device in Sleep Mode e Verify that J7 J13 and J14 do not have shorting blocks installed 3 I have been measuring the sleep mode current using the µA setting on my multimeter Why am I no longer able to connect to the IDE When most multimeters are placed in µA mode a large resistance is placed in series with the power s...

Page 22: ...s configuring a Port pin to analog mode using PnMDIN disables the digital input path and the weak pull up It does not explicitly disable the output drivers Software can ensure that the output drivers are disabled by configuring the Port pin to open drain output mode using PnMDOUT and writing 1 to the port latch 9 Why does power consumption increase when an analog signal hovering around mid supply ...

Page 23: ...ck source This causes the missing clock detector to time out and reset the MCU The proper way of changing the system clock when both the clock source and the clock divide value are being changed is as follows If switching from a fast undivided clock to a slower undivided clock a Change the clock divide value b Poll for CLKRDY 1 c Change the clock source If switching from a fast undivided clock to ...

Page 24: ...C8051F930 DK 24 Rev 0 5 9 Schematics Figure 10 C8051F930 Target Board Schematic Page 1 of 3 Downloaded from Elcodis com electronic components distributor ...

Page 25: ...C8051F930 DK Rev 0 5 25 Figure 11 C8051F930 Target Board Schematic Page 2 of 3 Downloaded from Elcodis com electronic components distributor ...

Page 26: ...C8051F930 DK 26 Rev 0 5 Figure 12 C8051F930 Target Board Schematic Page 3 of 3 Downloaded from Elcodis com electronic components distributor ...

Page 27: ...C8051F930 DK Rev 0 5 27 NOTES Downloaded from Elcodis com electronic components distributor ...

Page 28: ... for the functioning of undescribed features or parameters Silicon Laboratories reserves the right to make changes without further notice Silicon Laboratories makes no warranty rep resentation or guarantee regarding the suitability of its products for any particular purpose nor does Silicon Laboratories assume any liability arising out of the application or use of any product or circuit and specif...

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