Spartan-6 configuration speeds

Spartan-6 maximum JTAG clock is 18-33MHz according to "Table 3: Maximum JTAG Clock Frequencies" in [DS593] (v1.4, p. 8).

The Spartan-6 at speed grade -1L is limited to 18MHz, while other speed grades (-2, -3N, and -3) allows a TCK of 33MHz. See "Configuration Switching Characteristics" in [DS162] (v3.1.1, p. 54). Regarding the SelectMAP interface of the Spartan-6 LX9, the maximum configuration clock (CCLK) is 50MHz for speed grades -2 and above.

SelectMAP implementation

The implementation follows the documentation about "Microprocessor-Driven SelectMAP Configuration" from [UG380] (v2.7, p. 34) (further described in the old [XAPP502] and the newer [XAPP583]).

One important thing is to enable CCLK as configuration clock.

I am tryig to use the SelectMAP interface from the microconroller, but it is not working so far. I will update this post.

About bit swapping:

|                 0xAA99 | (config. word)
|       0xAA |      0x99 | (config. bytes)
|    A     A |    9    9 | (hex nibbles)
| 1010  1010 | 1001 1001 | (original bits)
| 0101  0101 | 1001 1001 | (swapped bits)
| D15 <-> D8 | D7 <-> D0 | (SelectMAP pins)

Update 2015.05.13

Apparantly, you have should use the .bin file for SelectMAP configuration (not the .bit file). I generated both and they have not the same content (as I previously expected).

The 16-bit parallel configuration (16x SelectMAP) from microcontroller now works, but I had to make an unexpected change on the clock CCLK termination resistors (2x 100Ω): remove the resistor to Vcc, while keeping the one to ground, so to lower the voltage of the clock. This goes against the recommendation of the Xilinx documentation [UG380].

What if ...?

I get status gives all bit at 0. Maybe PROGRAM_B is held low?

I send the configuration as serial data on D0 with mode settings for slave SelectMAP (M[1:0] = 10)? Actually, I works too. The slave serial setting (*``M[1:0] = 11``) is redundant.*

Persistant SelectMAP pins and readback settings


INFO:Bitgen:278 - Setting the Persist option to "Yes" with the CONFIG_MODE
constraint value "UnSpecified" will result in the 8-bit SelectMap port being persisted.

[UG625] (v14.5, p.70) "Configuration Mode". Strangely, according to this document, the Spartan-6 is not in the supported target devices. The option works anyway:

# SelectMAP slave, 16-bit mode with "Persist" option.