Cypress CY7C68013 ECC Generation7, Gpif, USB Uploads and Downloads, Autopointer Access, Eccm =

CY7C68013A, CY7C68014A CY7C68015A, CY7C68016A

3.13.3 GPIF and FIFO Clock Rates

An 8051 register bit selects one of two frequencies for the inter- nally supplied interface clock: 30 MHz and 48 MHz. Alternatively, an externally supplied clock of 5 MHz–48 MHz feeding the IFCLK pin can be used as the interface clock. IFCLK can be configured to function as an output clock when the GPIF and FIFOs are internally clocked. An output enable bit in the IFCONFIG register turns this clock output off, if desired. Another bit within the IFCONFIG register inverts the IFCLK signal whether internally or externally sourced.

3.15 ECC Generation[7]

The EZ-USB can calculate ECCs (Error Correcting Codes) on data that passes across its GPIF or Slave FIFO interfaces. There are two ECC configurations: Two ECCs, each calculated over 256 bytes (SmartMedia Standard); and one ECC calculated over 512 bytes.

The ECC can correct any one-bit error or detect any two-bit error.

3.15.1 ECC Implementation

The two ECC configurations are selected by the ECCM bit:

3.14 GPIF

The GPIF is a flexible 8-bit or 16-bit parallel interface driven by a user programmable finite state machine. It enables the CY7C68013A/15A to perform local bus mastering and can implement a wide variety of protocols such as ATA interface, printer parallel port, and Utopia.

The GPIF has six programmable control outputs (CTL), nine address outputs (GPIFADRx), and six general-purpose ready inputs (RDY). The data bus width can be 8 or 16 bits. Each GPIF vector defines the state of the control outputs, and determines what state a ready input (or multiple inputs) must be before proceeding. The GPIF vector can be programmed to advance a FIFO to the next data value, advance an address, etc. A sequence of the GPIF vectors make up a single waveform that is executed to perform the desired data move between the FX2LP and the external device.

3.14.1 Six Control OUT Signals

The 100-pin and 128-pin packages bring out all six Control Output pins (CTL0-CTL5). The 8051 programs the GPIF unit to define the CTL waveforms. The 56-pin package brings out three of these signals, CTL0–CTL2. CTLx waveform edges can be programmed to make transitions as fast as once per clock (20.8 ns using a 48-MHz clock).

3.14.2 Six Ready IN Signals

The 100-pin and 128-pin packages bring out all six Ready inputs (RDY0–RDY5). The 8051 programs the GPIF unit to test the RDY pins for GPIF branching. The 56-pin package brings out two of these signals, RDY0–1.

ECCM = 0

Two 3 byte ECCs, each calculated over a 256 byte block of data. This configuration conforms to the SmartMedia Standard.

Write any value to ECCRESET, then pass data across the GPIF or Slave FIFO interface. The ECC for the first 256 bytes of data is calculated and stored in ECC1. The ECC for the next 256 bytes is stored in ECC2. After the second ECC is calculated, the values in the ECCx registers do not change until ECCRESET is written again, even if more data is subsequently passed across the interface.

ECCM = 1

One 3 byte ECC calculated over a 512 byte block of data.

Write any value to ECCRESET then pass data across the GPIF or Slave FIFO interface. The ECC for the first 512 bytes of data is calculated and stored in ECC1; ECC2 is unused. After the ECC is calculated, the values in ECC1 do not change even if more data is subsequently passed across the interface, till ECCRESET is written again.

3.16 USB Uploads and Downloads

The core has the ability to directly edit the data contents of the internal 16 KByte RAM and of the internal 512 byte scratch pad RAM via a vendor specific command. This capability is normally used when soft downloading user code and is available only to and from internal RAM, only when the 8051 is held in reset. The available RAM spaces are 16 KBytes from 0x0000–0x3FFF (code/data) and 512 bytes from 0xE000–0xE1FF (scratch pad data RAM).[8]

3.14.3 Nine GPIF Address OUT Signals

Nine GPIF address lines are available in the 100-pin and 128-pin packages, GPIFADR[8..0]. The GPIF address lines enable indexing through up to a 512 byte block of RAM. If more address lines are needed IO port pins are used.

3.14.4 Long Transfer Mode

In the master mode, the 8051 appropriately sets GPIF trans- action count registers (GPIFTCB3, GPIFTCB2, GPIFTCB1, or GPIFTCB0) for unattended transfers of up to 232 transactions. The GPIF automatically throttles data flow to prevent under or overflow until the full number of requested transactions complete. The GPIF decrements the value in these registers to represent the current status of the transaction.

3.17 Autopointer Access

FX2LP provides two identical autopointers. They are similar to the internal 8051 data pointers but with an additional feature: they can optionally increment after every memory access. This capability is available to and from both internal and external RAM. The autopointers are available in external FX2LP registers under control of a mode bit (AUTOPTRSET-UP.0). Using the external FX2LP autopointer access (at 0xE67B – 0xE67C) enables the autopointer to access all internal and external RAM to the part.

Also, the autopointers can point to any FX2LP register or endpoint buffer space. When autopointer access to external memory is enabled, location 0xE67B and 0xE67C in XDATA and code space cannot be used.

Notes

7.To use the ECC logic, the GPIF or Slave FIFO interface must be configured for byte-wide operation.

8.After the data has been downloaded from the host, a “loader” can execute from internal RAM to transfer downloaded data to external memory.

Document #: 38-08032 Rev. *L Page 12 of 62

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