HI-6121PQMF HOLTIC [Holt Integrated Circuits], HI-6121PQMF Datasheet - Page 40

• Manufacturer Part Number: HI-6121PQMF
• Description: MIL-STD-1553 Remote Terminal ICs
• Manufacturer: HOLTIC [Holt Integrated Circuits]

DESCRIPTOR TABLE, Cont.
9
8
7-4
3
2
1
0
BCAST
PPON
CIR2ZN
STOPP
PPEN
CIR2EN
CIR1EN
indicates the buffer to be used for the next occurring transmit command to this subaddress. When the
DPB bit is logic 0, the next message will use Data Pointer A; when DPB is logic 1, the next message
uses Data Pointer B. In ping-pong buffer mode, the bit is inverted after each
completion. The DPB bit is not altered after messages ending in error, after illegal commands or after
messages when the terminal responds with Busy status. This bit is reset to logic 0 by
or SRST software reset; therefore the first message received after either reset will use Buffer A. This
bit is “don’t care” for indexed single-buffer mode or either circular buffer mode.
Broadcast Received.
The
Because non-mode broadcast-transmit commands are always illegal, the assertion of this bit in the
Control Word by the
depending on whether or not illegal command detection applies (any bits set in Illegalization Table).
This bit has no function if the BCSTINV bit is asserted in Configuration Register 1; in this case
commands to RT address 31 are not recognized as valid by the
MR
Ping-Pong Enable Acknowledge.
This bit is controlled by the device and should not be written by the host. It only applies if PPEN bit 2
was initialized to logic one by the host after reset, enabling ping-pong buffer mode for this
subaddress. The RT asserts this bit when it recognizes ping-pong is active for this subaddress.
Before loading the transmit data buffer for this subaddress, the host can ask the RT to temporarily
disable ping-pong by asserting STOPP bit 3. The RT acknowledges ping-pong is disabled by
negating PPON. The host can safely load the buffer without data collision while PPON is negated.
After buffer servicing, the host asks the RT to re-enable ping-pong by negating STOPP bit 3. The RT
acknowledges ping-pong is re-enabled by asserting PPON.
If PPEN bit 2 is high and PPON bit 8 is low when new commands arrive for this subaddress, ping-
pong is disabled. Each new message transmits data from the same buffer, specified by DPB bit 10,
and the DPB bit does not toggle after command completion.
Circular Mode 2 Zero Number.
Used only in circular buffer mode 2, this 4-bit field is initialized with the number of trailing zeros in the
initialized MIBA address. This is explained in a later section fully describing circular buffer mode 2.
Stop Ping-Pong Request.
The host asserts this bit to suspend ping-pong buffering for this subaddress. The host resets this bit to
ask the RT to re-enable ping-pong. The RT confirms recognition of ping-pong enable or disable
status by writing PPON bit 8. Refer to later section describing ping-pong mode for more information.
Ping-Pong Buffer Enable.
The PPEN, CIR1EN and CIR2EN bits are initialized by the host to select buffer mode.
explanation, see description below for bits 1-0.
After reset, the host initializes this bit to logic one to enable ping-pong buffering for this subaddress.
The host asserts STOPP bit 2 to ask the
STOPP bit asks the device to re-enable ping-pong. The device confirms ping-pong enable or disable
state changes by writing the PPON bit.
Circular Buffer Mode 2 Enable.
Circular Buffer Mode 1 Enable.
The PPEN, CIR1EN and CIR2EN bits are initialized by the host to select buffer mode. This table
summarizes how buffer mode selection is encoded:
master reset or SRST software reset.
device
PPEN
1
0
0
0
sets this bit when a broadcast-transmit command is received for this subaddress.
HOLT INTEGRATED CIRCUITS
device
HI-6120, HI-6121
Don’t care
indicates an illegal command was received. Terminal response varies,
CIR2EN
1
0
0
40
device
to temporarily disable ping-pong. Negating the
Don’t care
Don’t care
CIR1EN
1
0
device. This bit is reset to logic 0 by
Indexed Single Buffer
Circular Mode 2
Circular Mode 1
Buffer Mode
Ping-Pong
error-free
MR
master reset
message
For