Hi TI,
we have got a system which consists of 2 TDA4 SoC's. We want to use GTC on both TDA4 as a synchronoues timestamp. Therefore, we source the GTC module on both TDA4 with an external reference clock. This clock is provided by a FPGA and can be activated via SPI. In order to achieve a synchronous timestamp, we have to call the following commands on each of the TDA4:
- Disable GTC Counter
- Set Counter to Zero
- Change Clock Source to External Reference Clock
- Enable GTC Counter
- Send SPI command to activate External Reference Clock (Needs to be done only on one of the TDA4)
The problem with this approach is, that step 4 crashes, since at this time, the GTC module does not have a valid clock source, because only in step 5, the external reference clock is activated.
I have therefore the following questions about GTC module:
1. Is it possible to change the default behaviour of GTC module? At the moment, the GTC shows following behaviour at power-up: Counter is disabled and CTRLMMR_GTC_CLKSEL is set to 0 (internal clock). Desirable behaviour would be: GTC is enabled and CTRLMMR_GTC_CLKSEL is set to external ref clock.
2. Is there a minimum GTC_CLK frequency, which is accepted by GTC module?
3. Is it possible to reset GTC module from outside the TDA4?
Thanks for your help and best regards,
Felix
