Datasheet

www.ti.com EMAC Control Module Registers
31.3.13 EMAC Control Module Transmit Interrupts Per Millisecond Registers (C0TXIMAX)
The EMAC control module transmit interrupts per millisecond register (C0TXIMAX) is shown in
Figure 31-24 and described in Table 31-23
Figure 31-24. EMAC Control Module Transmit Interrupts Per Millisecond Register (C0TXIMAX)
(offset = 74h)
31 16
Reserved
R-0
15 6 5 0
Reserved TXIMAX
R-0 R/W-0
LEGEND: R/W = Read/Write; R = Read only; -n = value after reset
Table 31-23. EMAC Control Module Transmit Interrupts Per Millisecond Register (C0TXIMAX)
Bit Field Value Description
31-6 Reserved 0 Reserved
5-0 TXIMAX 2-3Fh TXIMAX is the desired number of C0TXPULSE interrupts generated per millisecond when
C0TXPACEEN is enabled in INTCONTROL.
The pacing mechanism can be described by the following pseudo-code:
while(1) {
interrupt_count = 0;
/* Count interrupts over a 1ms window */
for(i = 0; i < INTCONTROL[INTPRESCALE]*250; i++) {
interrupt_count += NEW_INTERRUPT_EVENTS();
if(i < INTCONTROL[INTPRESCALE]*pace_counter)
BLOCK_EMAC_INTERRUPTS();
else
ALLOW_EMAC_INTERRUPTS();
}
ALLOW_EMAC_INTERRUPTS();
if(interrupt_count > 2*TXIMAX)
pace_counter = 255;
else if(interrupt_count > 1.5*TXIMAX)
pace_counter = previous_pace_counter*2 + 1;
else if(interrupt_count > 1.0*TXIMAX)
pace_counter = previous_pace_counter + 1;
else if(interrupt_count > 0.5*TXIMAX)
pace_counter = previous_pace_counter - 1;
else if(interrupt_count != 0)
pace_counter = previous_pace_counter/2;
else
pace_counter = 0;
previous_pace_counter = pace_counter;
}
1583
SPNU562–May 2014 EMAC/MDIO Module
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