IEEE Std 1149.10 pdf free download

IEEE Std 1149.10 pdf free download. High-Speed Test Access Port and On-Chip Distribution Architecture.
Outbound response packets differ from the inbound packets by asserting bit 7 of the command byte high. An optional parity bit can be used on bit 6, hence that bit is reserved when that capability is enabled and documented in BSDL. Therefore, inbound commands 0x40-0x7F are also available when parity checking on the command is not used. The general format of both a send and a receive packet is shown in Figure 10. Packets begin with a Start-of-Packet (SOP) control character, followed by a command (CMD) byte, followed by the command-specific data (PAYLOAD), followed by the 32-bit CRC (CRC32), and terminated by four End-of-Packet (EOP) control characters. All packets have an integer multiple of four bytes up to the CRC32, followed by a CRC32 of four bytes and the four EOP bytes. A “packet frame” refers to any of the four bytes that start on an integer multiple of four. Other than the SOP character, control characters are sent in multiples of four before the next packet frame. A trade-off was made in requiring redundant control characters such as the four EOP characters in order to keep the packet aligned, which is thought to simplify the receiver decoding logic. The packet definitions are shown in this standard without regard to the encoding/decoding that may be implemented. This standard follows the convention of other serial standards such that the data in the packet is shown in human readable MSB to LSB, where the LSB is on the right without encoding. However, for many protocols, bits are transmitted with LSB first.
Figure 21 shows how the first data word is formed when all four channels are enabled in the packet. Each position represents one bit of a round-robin of each scan channel starting at Channel 0 followed by each channel in ascending order, padding as necessary until the SCAN_ _DATA_ SIZE (4 in this case) is reached. The BitO position is commonly transmitted first, so the bits are shown in that order (assuming there is no 8B/10B, 64B/66B, etc. encoding). Because there are just three bits to scan into each scan channel, the 2nd data byte must be padded to keep the data as two full bytes. Then two more bytes must be added to keep the scan payload a multiple of packet frames.
It may be desirable to implement a PEDDA that keeps the round- robin scan-channel sequence on nibble or byte boundaries. The bandwidth effciency lost by transmitting bit positions with no meaningful data may be a reasonable tradeoff with PEDDA design simplification. This is typical when the INTERLEAVE SIZE is an odd number, because SCAN data is expressed in packet frames. The PACKET MAP BSDL attribute presented earlier indicated that no packing of the scan data should be done (PACK is set to FALSE). This construct provides documentation for an automated software program to create a SCAN packet such that the bit positions for each scan-channel in the SCAN GROUP remain consistent and independently enabled. Figure 22 shows an example where only scan-channel 0, 2, and 3 are enabled. The position for scan- channel 1 is preserved, as the documentation indicates that there are four scan-channels in the group and the bits are not to be packed.IEEE Std 1149.10 pdf download.