From 77eafa89b4b9d8852071cc68298f92465311470b Mon Sep 17 00:00:00 2001 From: David Shah Date: Wed, 6 Dec 2017 17:48:15 +0000 Subject: HFOSC trimming info --- docs/ultraplus.html | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'docs/ultraplus.html') diff --git a/docs/ultraplus.html b/docs/ultraplus.html index 694b82d..dac648a 100644 --- a/docs/ultraplus.html +++ b/docs/ultraplus.html @@ -205,6 +205,14 @@ The CLKHF output of SB_HFOSC is conne

Configuration bit CLKHF_DIV[1] maps to DSP1 tile (0, 16) config bit CBIT_4, and CLKHF_DIV[0] maps to DSP1 tile (0, 16) config bit CBIT_3.

+

There is also an undocumented trimming function of the HFOSC, using the ports TRIM0 through TRIM9. This can only be accessed directly in iCECUBE if you modify the standard cell library. However + if you set the attribute VPP_2V5_TO_1P8V (which itself is not that well documented either) to 1 on the top level module, then the configuration bit + CBIT_5 of (0, 16) is set; and TRIM8 and TRIM4 are connected to + the same net as CLKHFPU.

+

TRIM[3:0] connect to (25, 28, lutff_[7:4]/in_0) and TRIM[9:4] + connect to (25, 29, lutff_[5:0]/in_3). CBIT_5 of (0, 16) must be set to enable trimming. The trim range +on the device used for testing was from 30.1 to 75.9 MHz. TRIM9 seemed to have no effect, the other inputs could broadly be considered to form a binary word, however it appeared neither linear +nor even monotonic.

SB_LFOSC

The CLKLFPU input connects through IPConnect tile (25, 29) input lutff_0/in_1; and the CLKLFEN input connects through input lutff_7/in_3 of the same tile.
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