RC Radio PWM signal, problems reading

Hi,

Im trying to resurrect this project from 2015 (Software AWD control for RC Cards using 4x brushless motors):

https://github.com/hammerfet/BrinirController

Ive built his VS2013 solution and got all that side working fine. However, next is to determine I can read the RC Radio signal (standard RC drone Turnigy 9x and FRSky V8FR-II receiver) and Im getting problems. The signals are just two, throttle and steering and connected to PA0 and PA1 on a STM32 F407 discovery.

Sometimes it doesnt read anything, sometimes it reads it once occasionally it reads everything fine.

Here is the IO code:

/* TIM2 Init - PPM Inputs */

htim2.Instance = TIM2;

htim2.Init.Prescaler = PPMMEASUREPRESCALER;

htim2.Init.CounterMode = TIM_COUNTERMODE_UP;

htim2.Init.Period = 65535;

htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;

HAL_TIM_Base_Init(&htim2);

sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;

HAL_TIM_ConfigClockSource(&htim2, &sClockSourceConfig);

sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;

sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;

HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig);

HAL_TIM_Base_Start_IT(&htim2);

and some more references in config.h:

  #define PPMMEASUREPRESCALER 4

  #define RECEIVERMINSIGNAL 500

  #define RECEIVERMIDSIGNAL 25000

  #define RECEIVERMAXSIGNAL 34000

Is there anything obviously wrong here? Anything I should know about connecting RC Radio PWM to the F407?