I've been looking for a too long time for the signification, usage, purpose of PORT_MCLK_COUNT located in the xn file. This is located on a 16-bit port, overlapping with ethernet.
Obviously, removing the definition in the xn file makes the build fail.
There is no trace of test point in any schematics. Nothing in the documentation, nothing on the forum. Just a line in main.xc:
Code: Select all
/* USB Packet buffering Core */
{
unsigned x;
thread_speed();
/* Attach mclk count port to mclk clock-block (for feedback) */
//set_port_clock(p_for_mclk_count, clk_audio_mclk);
#if(AUDIO_IO_TILE != XUD_TILE)
set_clock_src(clk_audio_mclk2, p_mclk_in2);
set_port_clock(p_for_mclk_count, clk_audio_mclk2);
start_clock(clk_audio_mclk2);
#else
/* Uses same clock-block as I2S */
asm("ldw %0, dp[clk_audio_mclk]":"=r"(x));
asm("setclk res[%0], %1"::"r"(p_for_mclk_count), "r"(x));
#endif