Which Serial PROMs Can I Use to Initialize
an E5 CSoC Device?

The Triscend E5 Configurable System-on-Chip (CSoC) family offers two primary means to initialize or configure the device at power-up.  The most common is parallel mode where the E5 connects directly to a standard byte-wide memory, such as Flash.

The other means is called serial mode.  The benefit of serial mode over parallel mode is that serial mode frees the seven D[7:1] data pins and the seventeen A[18:1] address pins, which provides 24 additional user-defined PIO pins.

When booting from a serial PROM, the E5 device requires a serial, sequential-access PROM like those commonly used to configure Field Programmable Gate Arrays (FPGAs).  The E5 does not support initialization from other commonly available serial PROM interfaces such as I²C, SPI, or MicroWire.  At the time the Triscend E5 family was designed, the serial, sequential-access PROMs were the only serial memories with sufficient density.

One disadvantage of the serial sequential-access PROMs is that they are usually more expensive than other comparable serial memories.  This is because FPGA vendors manufacture these devices and these PROMs are usually priced as part of a package with the FPGA device.  Buying these serial PROM devices separately may be more expensive than using standard byte-wide Flash.

Table 1 shows the various serial PROM families that are supported by the Triscend E5 family.  The Atmel AT17xxx family is the only one that is in-system programmable via the E5’s JTAG interface using FastChip.  The Xilinx XC17xxx family requires an external device programmer.  The Xilinx XC18xxx family is in-system programmable via JTAG, but not using FastChip.

Table 1.  Serial PROMs Supported by Triscend E5 CSoC.

Vendor	Device Family	In-System Programmable?	Available Bit Densities
Atmel	AT17xxx	Yes, using FastChip and E5 JTAG interface	64K to 4M
Xilinx	XC17E00 XC17L00 XC17S00 XC17V00	No, requires external PROM programmer	36K to 256K 64K to 4M 52K to 1M 1M to 16M
Xilinx	XC18V00	Via JTAG, but not using FastChip	256K to 4M

The Triscend E5 does not support the Atmel AT17xxxA device family—note the ‘A’ suffix.  These devices are specifically designed to work with Altera FPGAs.

FastChip assumes that serial PROM’s reset is active High. External serial PROM programmers should set this option accordingly, and products should be designed assuming an active-High reset to the PROM.

Your serial PROM distributor can provide the parts pre-programmed with your application for a small additional charge.  Just provide your distributor with the *.hex file output from FastChip’s Configuration utility.

What Size Serial PROM is Required?

When operating in serial mode, the application for the embedded 8051 is copied from the serial PROM into the E5’s internal SRAM and then executed from there.  Consequently, the largest serial PROM required for a given device is one large enough to hold the CSoC configuration image and code to fill the entire internal SRAM, as shown in Table 2.

Table 2.  Maximum Serial PROM Bits Required by Device.

Device	CSoC Image	Code Space	Max. Image	Max. PROM Bits
TE502	13,261	8,192	21,453	171,624
TE505	22,237	16,384	38,621	308,968
TE512	43,645	32,768	76,413	611,304
TE520	72,445	40,960	113,405	907,240

However, in most applications, the internal SRAM will be shared with data storage so the actual maximum image will be less.  The smallest code space would be just 18 bytes, which is the size of the housekeeping program loaded by FastChip if you do not specify an application program when you create a configuration image.

To determine the actual PROM size required for your specific application, add the two sizes from the bottom of the Configuration Report File (*.cfr), which is created when you generate a Configuration image.  An example configuration report is shown in Figure 1.

Memory Map of Serial Memory (origin at 0x0)

===========================================

Secondary initialization code:

base address = 0x0000_0000

size         = 0x0000_33cd

entry point  = 0x0000_0000

User code:

base address = 0x0000_33cd

size         = 0x0000_085b

entry point  = 0x0000_33cd

===========================================

Figure 1.  Configuration Image and Code Size Shown in Configuration Report File (*.cfr)

Atmel AT17xxx Interface

Figure 2 shows an example interface between a Triscend E5 device and an Atmel AT17xxx serial PROM.  You can download the E5 configuration data and your application program into the serial PROM using FastChip.  FastChip programs the Atmel serial PROM via the E5’s JTAG interface, which in turn drives the E5’s Memory Interface Unit (MIU) connected to the serial PROM.  The two 4.7 k-ohm resistors are required to program the Atmel serial PROM.

The connections indicated with an asterisk (*) depend on the specific serial PROM device and your application environment.  Please refer to the relevant Atmel data sheet for additional information.

Figure 2.  Triscend E5 interface to Atmel AT17xxx serial PROM.

The Triscend E5 interfaces to both 5-volt and 3.3-volt serial PROMs.

Xilinx XC17xxx Interface

Figure 3 shows an example interface to a Xilinx XC17xxx serial PROM.  The Xilinx XC17xxx serial PROMs are not in-system programmable.  They must be programmed using an external device programmer before being mounted on the board.  Be sure to connect the serial PROM’s VPP to it VCC value for proper operation.

Figure 3.  Triscend E5 interface to Xilinx XC17xxx serial PROM.

FastChip Version: 2.4.0

This solution may or may not apply to other versions of the FastChip development system.

®

© 2002 by Triscend Corporation.  All rights reserved.