~~TOC:3-4~~
===== UniversalTx Hardware Connections =====
The following documents the hardware inside the UniversalTx transceiver board
  * MCU: [[http://www.st.com/web/catalog/mmc/FM141/SC1169/SS1574/LN1823/PF259605|STM32F072RB]] 128kB Flash, 16kB RAM 48pin package
  * Radio:
    * CYRF6936 2.4GHz
    * CC2500 2.4GHz
    * A7105 2.4GHz
    * NRF24L01 2.4GHz 

==== STM32 Connections ====
^Pin    ^Description        ^
|BOOT0  |CON2               |
|NRST   |Debugger (NRESET)  |

=== GPIOA ===
^Pin         ^Description                                      ^
|0           |PPMin/USART4 (can be used as single-wire bi-di)  |
|1           |PA Enable input from NRF24L01                    |
|2           |Bluetooth UART Tx                                |
|3           |Bluetooth UART Rx                                |
|4           |Bluetooth STATE input (connection detect)        |
|7           |Bluetooth Key output                             |
|8           |UniversalTx CSN                                  |
|9           |CYRF6936 CSN                                     |
|10          |USB D-                                           |
|11          |USB D+                                           |
|12          |SWDIO                                            |
|13          |SWCLK                                            |
|14 (SWCLK)  |Debugger SWCLK (TCK)                             |
|15          |Mux Select 1                                     |

=== GPIOB ===
^Pin  ^Description              ^
|2    |BOOT1                    |
|3    |Mux Select 2             |
|6    |NRF24L01 CSN             |
|7    |VBUS (USB Power Detect)  |
|8    |NRF24L01 ChipEnable      |
|9    |A7105 CSN                |
|10   |PA Tx Enable             |
|11   |PA Rx Enable             |
|12   |Pasthrough CSN input     |
|13   |SCK                      |
|14   |MISO                     |
|15   |MOSI                     |

==== Interrupt usage ====
|SYSTICK  |Priority 0                                                                |
|EXTI0    |Pritority128 - PPM In edge detect                                         |
|EXTI2    |Priority 0 - Watchdog (currently not enabled)                             |
|TIM14    |Priority 64 - Transmit timer                                              |
|EXTI8    |Priority 0 - UniversalTx CSN                                              |
|EXTI12   |Priority 0 - Passthrough CSN                                              |
|ADC      |Priority 0 - ADC compare complete (set PA Tx/Rx based on NRF24L01 PA_EN)  |


==== Timers ====
|TIM1   |PPM In pulse counter  |
|TIM14  |Transmit timer        |