MK50H28 datasheet(30/64 Pages) STMICROELECTRONICS

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TIMER

DESCRIPTION

User N392 /

nN2

Number of errors occuring on the LMI channel before an alarm is declared. In non-Auto

LMI Mode, timer time-outs are ignored and nN2 is only incremented when a STATUS

frame is received with bad sequence number. In Auto LMI User & Bi-directional mode this

is the User N392. The range for N392/nN2 must be 1 - 10 events.

User N393 /

nN3

Measurement interval for N392/nN2. An alarm will be declared if there are errors in nN2

of the last nN3 LMI events. In non-Auto LMI Mode, timer time-outs are ignored and nN3

window is only advanced when a STATUS frame is received In Auto LMI User & Bi-

directional mode this is the User N393. NOTE: nN2 must be less than or equal to nN3 and

the range of nN3 must be 1 - 10 events.

Ntwk N392

Network N392. In Auto LMI Network & Bi-directional mode, this is the number of errors

occuring on the LMI channel before an alarm is declared.

Ntwk N393

Network N393. In Auto LMI Network & Bi-directional mode, this is the measurement

interval for Ntwk N392. NOTE: Ntwk N392 and N393 are updated for LMI frames

received with second set of sequence numbers in Bi-directional mode

dN1

MAXIMUM FRAME LENGTH. This field must contain the two’s complement of one less

than the maximum allowable frame length, in bytes. Any frame that exceeds this count

will be discarded. NOTE: The DLCI header and CRC are included in the maximum frame

length count.

nN1 /

N391

The rate at which Full STATUS_ENQUIRY frame is sent to the network by the MK50H28

upon hosts request. This field must contain the two’s complement of one less than the

desired value. If CSR2<14> bit EIBEN =1, the MK50H28 will expect the value for nN1

counter to be located in the upper byte of IADR+40.

SCALER

TIMER PRESCALER. Timers nT1, nT2 and TP are scaled by this number. The

prescaler is incremented once every 32 system clock pulses. When it reaches zero the

timers are incremented and the prescaler is reset. This field is interpreted as the two’s

complement of the prescaler period. If CSR2<14> bit EIBEN =1, the MK50H28 will use

the entire 16-bit value at IADR+08 as the prescaler value. This may be required to

achieve longer timer values when operating at high SYSCLK speeds. NOTE: a prescale

value of one gives the smallest amount of scaling to the timers (64 clock pulses), zero

gives the largest (8224 clock pulses if EIBEN=0, or 2,097,184 clock pulses if EIBEN=1).

nT1 /

T391

USER POLL TIMER. In Auto LMI mode, the nT1/T391 timer is started when a

STATUS ENQUIRY frame is transmitted. Following the expiration of this timer, the device

transmits another STATUS ENQUIRY frame and increments the nT1/T391 Timeout Error

Counter if a STATUS frame was not received within the polling interval. This is not valid

for LMI frames with second set of sequence numbers. In non-Auto LMI mode, the

nT1/T391 timer is started by issuing a Start Timer nT1/T391 user primitive 8. Only in this

mode, does the device issue a Timer Expiration provider primitive 8 indicating that the

nT1/T391 timer has expired. This field must contain the two’s complement of the period

of the Timer nT1. NOTE: nT1/T391 must be less than nT2/T392.

nT2 /

T392

NETWORK POLL TIMER. In Auto LMI mode, the nT2/T392 timer is started when a

STATUS frame is transmitted. Following the expiration of this timer the device increments

the nT2/T392 Timeout Error Counter if a STATUS ENQUIRY frame was not received

within the poll interval. This is not valid for LMI frames with second set of sequence

numbers. In non-Auto LMI mode the nT2/T392 timer is started by issuing a Start Timer

nT2 user primitive 9. Only in this mode, does the device issue a Timer Expiration

provider primitive 9 indicating that the nT2 timer has expired. NOTE: nT2/T392 must be

greater than nT1/T391.

TRANSMIT POLLING PERIOD. This scaled timer works on the Context Table on a per

channel basis. No attempt to transmit a frame on a link is made until TP expires. When

the TP expires the MK50H28 will first check to see whether the next channel is ready (i.e.,

TXRDY = 1). If TXRDY is set, it will service that channel. Then it will either jump, based

on ENIDX bit being set, or continue to the next sequential channel. The MK50H28 will

continue this process until it finds a CT Entry with the EOR bit set, causing the device to

go to the begining of the CT and service the first Non-LMI channel. This field must contain

two’s complement of the period of the timer TP. NOTE: Once the MK50H28 finishes

servicing a channel (transmitting frames), it waits for TP to expire before begining to poll

for the next available channel that has frames to be transmitted. The MK50H28 continues

its search from channel to channel, without waiting for TP to expire, until it finds the next

available channel that has frames to be transmitted. Setting the TDMD bit causes the

MK50H28 to immediately begin polling without waiting for TP to expire.

MK50H28

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