2-34
Functional Description
2.2.9 JTAG Boundary Scan Testing
With one exception, the SYM53C1010 includes support for JTAG
boundary scan testing in accordance with the IEEE 1149.1 specification.
The exception concerns the TST_RSTN pin. This pin must not be
toggled as it will reset the JTAG TAP controller. For more information,
refer to the BSDL (Boundary Scan Descriptor Language) file.
This device accepts all required boundary scan instructions including the
optional CLAMP, HIGH-Z, and IDCODE instructions. The optional JTAG
pin TRST is not implemented. Reset of the JTAG logic through the TAP
controller occurs when TMS is held high for at least 5 TCK clock cycles.
The SYM53C1010 uses an 8-bit instruction register to support all
boundary scan instructions. The data registers included in the device are
the Boundary Data register, the IDCODE register, and the Bypass
register. This device can handle a 20 MHz TCK frequency with all TAP
pins having a 50% duty cycle.
2.2.10 Parity/CRC/AIP Options
The SYM53C1010 implements a flexible parity scheme that permits
control of the parity sense, allows parity checking to be turned on or off,
and can deliberately send a byte with bad parity over the SCSI bus.
Table
2.5
defines the bits that are involved in parity control and observation.
Table 2.6
describes the parity control function of the Enable Parity
Checking and Assert SCSI Even Parity bits in the
SCSI Control One
(SCNTL1)
register, bit 2.
SCRIPTS RAM must first be written before being read in order to
initialize SCRIPTS RAM parity. If a SCRIPTS RAM parity error is
encountered, a SCSI Gross Error interrupt will be signaled.
The SYM53C1010 supports CRC checking and generation in DT phases
and CRC checking and generation during DT Data Transfers.
The new CRC registers are
CRC Pad Byte Value (CRCPAD)
,
CRC
Control Zero (CRCCNTL0)
,
CRC Control One (CRCCNTL1)
,
CRC Data
(CRCD)
,
SCSI Control Zero (SCNTL0)
, bit 3; EPC (Enable
Parity/CRC/AIP checking), bit 1; AAP (Assert SATN/ on Parity/CRC/AIP
error);
SCSI Control One (SCNTL1)
, bit 5; DHP (Disable Halt on