Hello;
I am working with CCS v5 and with a Beaglebone Black, running my example into the CortxA8. I am trying to communicate with an 8-channel 24-bit ADC from T.I. (ADS1278). For that, I need to generate a 27 MHz clock in my Beaglebone. I want to do it using one of my DM Timers (Timer4, in this case). As it is impossible to generate that frequency using the internal clocks, I need to introduce an external clock from an oscilator to my beaglebone and reuse it to generate my own timer. However, I am having some troubles with the Starterware programming.
In theory, I have to change DMTimer4ModuleClkConfiguration() to select CM_DPLL_CLKSEL_TIMER3_CLK_CLKSEL_SEL1 instead of CM_DPLL_CLKSEL_TIMER3_CLK_CLKSEL_CLK_M_OSC (the "internal" clock).
Also, I have to configure the muxmode of TCLKIN pin in the P9 connector of the beaglebone. I configure it like this.
Hello;
I am working with CCS v5 and with a Beaglebone Black, running my example into the CortxA8. I am trying to communicate with an 8-channel 24-bit ADC from T.I. (ADS1278). For that, I need to generate a 27 MHz clock in my Beaglebone. I want to do it using one of my DM Timers (Timer4, in this case). As it is impossible to generate that frequency using the internal clocks, I need to introduce an external clock from an oscilator to my beaglebone and reuse it to generate my own timer. However, I am having some troubles with the Starterware programming.
In theory, I have to change DMTimer4ModuleClkConfiguration() to select CM_DPLL_CLKSEL_TIMER3_CLK_CLKSEL_SEL1 instead of CM_DPLL_CLKSEL_TIMER3_CLK_CLKSEL_CLK_M_OSC (the "internal" clock).
Also, I have to configure the muxmode of TCLKIN pin in the P9 connector of the beaglebone. I configure it like this.
/* Setup up pinmux for TCLK muxmode 2*/
HWREG(SOC_CONTROL_REGS + CONTROL_CONF_XDMA_EVENT_INTR(1)) =
(2 << CONTROL_CONF_XDMA_EVENT_INTR0_CONF_XDMA_EVENT_INTR0_MMODE_SHIFT) |
(0 << CONTROL_CONF_XDMA_EVENT_INTR0_CONF_XDMA_EVENT_INTR0_PUDEN_SHIFT) |
(1 << CONTROL_CONF_XDMA_EVENT_INTR0_CONF_XDMA_EVENT_INTR0_PUTYPESEL_SHIFT)|
(1 << CONTROL_CONF_XDMA_EVENT_INTR0_CONF_XDMA_EVENT_INTR0_RXACTIVE_SHIFT) |
(0 << CONTROL_CONF_XDMA_EVENT_INTR0_CONF_XDMA_EVENT_INTR0_SLEWCTRL_SHIFT);
However, with these changes the program does not work. How can I configure the Timer4 to use an external TCLKIN? And, what might be even more important, which are the limits in frequency that can work with the TCLKIN option?
