Texas Instruments TNETE211 manual LdTmr, LdThr, ChSel must indicate the selected transmit channel

Adapter Host Registers

Table A±5. Host_CMD Register Bits (Continued)

Bit	Name	Function
14	Ld_Tmr	Load interrupt timer4: Writing a 1 to this bit causes the interrupt holdoff timer to be loaded
		from the Ack Count field. Ack Count indicates the time-out period in 4-∝s units (based
		on a 33-MHz PCI clock). The interrupt holdoff timer is used to pace interrupts to the host.
		Host interrupts are disabled (PCI interrupt request line deasserted) for the time-out peri-
		od of the timer after an Ack bit write. The timer is restarted on every Ack bit write.
13	Ld_Thr	Load Tx interrupt threshold5: Writing a 1 to this bit causes selected transmit channel
		interrupt threshold to be loaded from the Ack count field. For this operation to be valid
		(take effect), the following parameters must be set: Nes = 0, EOC = 0, R/T = 0, and
		Ch_Sel must indicate the selected transmit channel.
		Set Ack count to indicate the Tx interrupt threshold in number of EOF interrupts. This
		threshold determines the number of Tx EOF interrupts that must occur before a Tx EOF
		interrupt is posted. If the threshold is set to 0, no Tx EOF interrupts are posted.
12	Req_Int	Request host interrupt: Writing a 1 to this bit creates a dummy ThunderLAN interrupt.
		Writing a 0 to this bit has no effect. This bit is always read as 0.
11	Ints_off	Turn PCI interrupts off: Writing a 1 to this bit disables ThunderLAN interrupts to the host
		(PINTA# will never be asserted). Writing a 0 to this bit has no effect. This bit is always
		read as 0.
10	Ints_on	Turn PCI interrupts on: Writing a 1 to this bit reenables ThunderLAN interrupts after an
		Ints_off command bit write. Writing a 0 to this bit has no effect. This bit is always read
		as 0.
9±8	0	These bits are reserved and are always written as 0s.
7±0	Ack count	EOF acknowledge count: This field is primarily used to acknowledge Rx or Tx EOF in-
		terrupts in conjunction with the Ack command bit. It is set with the number of frames
		(lists) serviced by the host interrupt routine in response to the interrupt. The adapter

then uses this parameter to determine if the host has serviced all outstanding frame in- terrupts, and therefore, whether to generate a further EOF interrupt.

This field is also used to pass interrupt threshold and timer values in conjunction with the Ld_Tmr and Ld_Thr command bits.

4)The interrupt timer value may be reloaded at any time. If the timer had already timed out, it remains that way. If it has not yet timed out, it does so when the new timer value is reached or surpassed.

5)The threshold value may be reloaded at any time. Increasing the threshold value causes a current interrupt to be deasserted if the old threshold value has been reached and the new threshold hasn't.

A-16