Texas Instruments CC2520, User Manual

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interval, indicating that the boot loader is running. Use this method to check whether you have
a working boot loader or not.
If the LED D6 blinks with a faster frequency (10 times per second) the boot loader could not
find a valid application to boot.
The same LED will be on when the firmware is running (indicating OK).
When the boot loader is running, the only functionality that is offered from SmartRF Studio
and SmartRF Flash Programmer is to load a new version of the standard firmware.
7.1.2 USB MCU pin out
The following table shows the usage of I/O pins on the USB MCU.
Pin Function Description
P0.0 SPI_SELECT /JOY_LEVEL
Function depending on switch P21:
NORMAL: When SPI_SELECT is set LOW, it enables a special CC2520 sniffer
interface (for test and diagnostic purposes.
CC2511JOY: Joystick level is an analog value that can be decoded to find the
actual position of the joystick (centre, up, left, right or down)
P0.1 USB_EM_RESET Signal used to reset the EM board
P0.2 USB_CS SPI Chip select for device on EM board
P0.3 USB_SCLK SPI Clock
P0.4 USB_MOSI SPI MOSI (master out, slave in)
P0.5 USB_MISO SPI MISO (master in, slave out)
P1.0 USB_IFC_CTRL
Enables the USB interface when it is set high. Set either by the boot loader or
the firmware.
P1.1 USB_DBG_DC
Debug clock – used when CC2511 communicates with another LPW Soc via
the debug interface.
P1.2 USB_UART_RTS/USB_LED Dual function: UART Ready To Send and output signal for control of LED D6.
P1.3 USB_UART_CTS/USB_BUTTON Dual function: UART Clear To Send and input signal for USB button event.
P1.4 USB_UART_TX UART TX
P1.5 USB_UART_RX UART RX
P1.6 DGB_DD_DIR /JOY_MOVE
Function depending on switch P21:
NORMAL: The debug data direction signal controls the signal flow on the level
converter for the external debug interface.
CC2511JOY: Joystick move signal input. Set high on any joystick event
(pushed, moved up, left, right or down)
P1.7 USB_DBG_DD
Debug data – used when CC2511 communicates with another LPW SoC via
the debug interface.
P2.0 USB_LCD_FLASH_RESET Resets both the serial flash and the LCD on the board when it is set low.
P2.1 CC2511 DBG DD CC2511 debug interface
P2.2 CC2511 DBG DC CC2511 debug interface
P2.3 LCD_MODE Selects operating mode of the LCD
P2.4 LCD_CS SPI Chip select signal for the LCD
Table 1 - USB MCU pin-out
As mentioned in the table, the joystick output is coded as an analogue voltage. This has been
done in order to save the number of pins required on the MCU to interface with the joystick.