Cypress CYV15G0404RB manual Power Control, Device Configuration and Control Interface

CYV15G0404RB

reclocker serial drivers for a channel are in this disabled state, the associated internal reclocker logic also powers down. The deserialization logic and parallel outputs remain enabled. A device reset (RESET sampled LOW) disables all output drivers.

Note When the disabled reclocker function (that is, both outputs disabled) is reenabled, the data on the reclocker serial outputs may not meet all timing specifications for up to 250 ∝s.

Output Bus

Each receive channel presents a 10-bit data signal (and a BIST status signal when RXBISTx[1:0] = 10).

Receive BIST Operation

Each receiver channel contains an internal pattern checker that is used to validate both device and link operation. These pattern checkers are enabled by the associated RXBISTx[1:0] latch through the device configuration interface. When enabled, a register in the associated receive channel becomes a signature pattern generator and checker by logically converting to a Linear Feedback Shift Register (LFSR). This LFSR generates a 511-character sequence. This provides a predictable, yet pseudorandom, sequence that can be matched to an identical LFSR in the attached Transmitter(s). When synchronized with the received data stream, the associated Receiver checks each character from the deseri- alizer with each character generated by the LFSR and indicates compare errors and BIST status at the RXDx[1:0] and BISTSTx bits of the Output Register.

The BIST status bus {BISTSTx, RXDx[0], RXDx[1]} indicates 010b or 100b for one character period per BIST loop to indicate loop completion. Use this status to check test pattern progress.

Table 5, “Receive BIST Status Bits,” on page 17 lists the specific status reported by the BIST state machine. The receive status outputs report these same codes.

If the number of invalid characters received exceeds the number of valid characters by 16, the receive BIST state machine aborts the compare operations and resets the LFSR to look for the start of the BIST sequence again.

A device reset (RESET sampled LOW) presets the BIST Enable Latches to disable BIST on all channels.

BIST Status State Machine

When a receive path is enabled to look for and compare the received data stream with the BIST pattern, the {BISTSTx, RXDx[0], RXDx[1]} bits identify the present state of the BIST compare operation.

The BIST state machine has multiple states, as shown in Figure 2, "Receive BIST State Machine," on page 18 and Table 5, “Receive BIST Status Bits,” on page 17. When the receive PLL detects an out-of-lock condition, it forces the BIST state to the Start-of-BIST state, regardless of the present state of the BIST state machine. If the number of detected errors ever exceeds the number of valid matches by greater than 16, the state machine is forced to the WAIT_FOR_BIST state, where it monitors the receive path for the first character of the next BIST sequence.

Power Control

The CYV15G0404RB supports user control of the powered up or down state of each transmit and receive channel. The RXPLLPDx latch controls the receive channels through the device configuration interface. RXPLLPDx = 0 disables the associated PLL and analog circuitry of the channel. The OE1x and the OE2x latches control the transmit channels via the device configuration interface. The ROE1x and the ROE2x latches control the reclocker function through the device configuration interface. When the configuration interface disables a driver, the driver internally powers down to reduce device power. If both serial drivers for a channel are in this disabled state, the associated internal logic for that channel also powers down. The reclocker serial drivers being disabled in turn disables the reclocker function, but the deserialization logic and parallel outputs remain enabled.

Device Reset State

Assertion of RESET resets all state machines, counters, and configuration latches in the device to a reset state. Additionally, the JTAG controller must be reset for valid operation (even if not performing JTAG testing). See “JTAG Support” on page 17 for JTAG state machine initialization. See Table 3, “Device Configuration and Control Latch Descrip- tions,” on page 14 for the initialize values of the configuration latches.

Following a device reset, enable the receive channels used for normal operation. Do this by sequencing the appropriate values on the device configuration interface.[3]

Device Configuration and Control Interface

Configure the CYV15G0404RB through the configuration interface. The configuration interface enables the device to be configured globally or enables each channel to be configured independently. Table 3, “Device Configuration and Control Latch Descriptions,” on page 14 lists the configuration latches within the device, including the initialization value of the latches on the assertion of RESET. Table 4, “Device Control Latch Configuration Table,” on page 16 shows how the latches are mapped in the device. Each row in Table 4 maps to an 8-bit latch bank. There are 16 such write only latch banks. When WREN = 0, the logic value in the DATA[7:0] latches to the latch bank specified by the values in ADDR[3:0]. The second column of Table 4 specifies the channels associated with the corresponding latch bank. For example, the first three latch banks (0, 1, and 2) consist of configuration bits for channel A. Latch banks 12, 13, and 14 consist of Global configuration bits, and the last latch bank (15) is the Mask latch bank, which can be configured to perform bit-by-bit configuration.

Global Enable Function

The global enable function, controlled by the GLENx bits, is a feature that can reduce the number of write operations needed to set up the latch banks. This function is beneficial in systems that use a common configuration in multiple channels. The GLENx bit is present in bit 0 of latch banks 0 through 11 only. Its default value (1) enables the global update of the latch bank's contents. Setting the GLENx bit to 0 disables this functionality.

Document #: 38-02102 Rev. *C Page 13 of 27

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