Problem with priority handling.

Simon,

My understanding of the function of priorities (channel numbers) in the Vectored Interrupt Manager (VIM) is that they only determine which interrupt to service when multiple interrupts are pending simultaneously. The VIM does not appear to automatically suppress lower priority interrupts while a particular interrupt is being serviced.

The Hwi module for the TMS570 does provide a mechanism for controlling which interrupts are enabled while a particular interrupt is being serviced by means of the enumerated "maskSetting" instance config parameter.

By default, the maskSetting parameter is set to Hwi.MaskingOption_SELF which results in all but the current interrupt being enabled while it is being serviced.

Other settings are:

1) MaskingOption_NONE, which enables ALL interrupts (including the interrupt-under-service) while the current interrupt is being serviced.

2) MaskingOption_ALL, which disables ALL interrupts while the current interrupt is being serviced (this may be what you want to use for 20KHz Timer interrupt).

3) MaskingOption_BITMASK, which, combined with the disableMask0, disableMask1, restoreMask0, and restoreMask1 bit mask parameters allow you to precisely control which interrupts are disabled while an interrupt is being serviced.

4) Some device interrupt architectures (unfortunately not the VIM) also support MaskingOption_LOWER, which would yield the behavior you want.

To control the Hwi settings for the Timer instances, use the Timer.Params.hwiParams config parameter. Here is an example I think might work for you:

 var Hwi = xdc.useModule('ti.sysbios.family.arm.tms570.Hwi');
 var Timer = xdc.useModule('ti.sysbios.family.arm.tms570.Timer');

 var timerParams = new Timer.Params()

 timerParams.hwiParams = new Hwi.Params();

 timerParams.period = 50;    /* 50us = 20 KHz */
 timerParams.hwiParams.maskSetting = Hwi.MaskingOption_ALL; /* don't allow nesting  */

 Timer.create(Timer.ANY, '&myTimerFunc', timerParams);