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authorKeith Rothman <537074+litghost@users.noreply.github.com>2021-04-05 13:47:15 -0700
committerKeith Rothman <537074+litghost@users.noreply.github.com>2021-04-05 14:00:26 -0700
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Iterate DeviceResources doc with feedback from review.
Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>
Diffstat (limited to 'docs')
-rw-r--r--docs/device_resources.md137
1 files changed, 134 insertions, 3 deletions
diff --git a/docs/device_resources.md b/docs/device_resources.md
index 9770440..1d8efec 100644
--- a/docs/device_resources.md
+++ b/docs/device_resources.md
@@ -89,14 +89,145 @@ end at an input/inout BEL pin. If a net enters a site, that net **must** end
at an input/inout BEL pin. It is not legal for a net to enter and leave a
site. If such a path is required, a pseudo PIP should be added to the schema.
+## Site example
+
+The following is an example site for a SLICE for a non-existant device.
+
+```
+ ▲
+ CO│ │
+ ┌──────────────────────────┼─────────────────────────────────────┼──────┐
+ │ │ │ │
+ B0│ I0┌───────┐ │ BLUT ┌───────┐ ▼ CLK │
+─────┼────►│ │ ┌────────o─────────────────┬────►│ │ ┌────┐ │
+ B1│ I1│ │O │ │ │XOR │ │D D│ │Q │ FFOUT
+─────┼────►│ BLUT3 ├───┤ │ ┌────────┬──o────►│ FFMUX ├──►│ FF ├───┼───►
+ B2│ I2│ │ │ │ │ │ |ALUT │ │ │ │ │
+─────┼────►│ │ │ │ │ ┌──┬──o──o────►│ │ └────┘ │
+ │ └───────┘ │ ┌───┴───┐ │ │ │ │ │ └───────┘ │
+ │ │ SI│ │ │ │ │ │ │ │
+ │ └───►│ ├─┘ │ │ │ │ │
+ │ DX│ CARRY │ O │ │ │ │ │
+ │ ┌───►│ │ │ │ │ │ │
+ A0│ I0┌───────┐ │ └───┬───┘ │ │ │ │ ┌────────┐ │
+─────┼────►│ │ │ │ │ │ │ │ BLUT │ │ │
+ A1│ I1│ │O │ │ │ │ │ └─────►│ │OUT │ OUT
+─────┼────►│ ALUT3 ├───┴────────o────────┘ │ │ XOR │ OUTMUX ├──────────┼────►
+ B2│ I2│ │ │ │ └────────►│ │ │
+─────┼────►│ │ │ │ ALUT │ │ │
+ │ └───────┘ │ └───────────►└────────┘ │
+ │ │ │
+ │ │ │
+ └──────────────────────────┼────────────────────────────────────────────┘
+ CI│
+ │
+```
+
+In the above example, there 17 BELs:
+
+| BEL Name | Category | # Input | # Output |
+|----------|-----------|---------|----------|
+| ALUT3 | Logic | 3 | 1 |
+| BLUT3 | Logic | 3 | 1 |
+| CARRY | Logic | 3 | 2 |
+| FF | Logic | 2 | 1 |
+| FFMUX | Routing | 3 | 1 |
+| OUTMUX | Routing | 3 | 1 |
+| A0 | Site port | 0 | 1 |
+| A1 | Site port | 0 | 1 |
+| A2 | Site port | 0 | 1 |
+| B0 | Site port | 0 | 1 |
+| B1 | Site port | 0 | 1 |
+| B2 | Site port | 0 | 1 |
+| CI | Site port | 0 | 1 |
+| CLK | Site port | 0 | 1 |
+| CO | Site port | 1 | 0 |
+| FFOUT | Site port | 1 | 0 |
+| OUT | Site port | 1 | 0 |
+
+Each site port BEL has a site pin, so the site pins are:
+
+| Site Pin Name | Direction |
+|---------------|-----------|
+| A0 | In |
+| A1 | In |
+| A2 | In |
+| B0 | In |
+| B1 | In |
+| B2 | In |
+| CI | In |
+| CLK | In |
+| CO | Out |
+| FFOUT | Out |
+| OUT | Out |
+
+The BEL BLUT3 has 4 BEL pins:
+
+| BEL pin name | Direction |
+|--------------|-----------|
+| I0 | In |
+| I1 | In |
+| I2 | In |
+| O | Out |
+
+The BEL A0 has 1 BEL pin:
+
+| BEL pin name | Direction |
+|--------------|-----------|
+| A0 | Out |
+
+The BEL OUTMUX has 4 BEL pins:
+
+| BEL pin name | Direction |
+|--------------|-----------|
+| BLUT | In |
+| XOR | In |
+| ALUT | In |
+| OUT | Out |
+
+
+There are 12 site PIPs:
+
+| BEL name | In pin | Out pin |
+|----------|--------|---------|
+| BLUT3 | I0 | O |
+| BLUT3 | I1 | O |
+| BLUT3 | I2 | O |
+| ALUT3 | I0 | O |
+| ALUT3 | I1 | O |
+| ALUT3 | I2 | O |
+| FFMUX | ALUT | D |
+| FFMUX | XOR | D |
+| FFMUX | BLUT | D |
+| OUTMUX | ALUT | OUT |
+| OUTMUX | XOR | OUT |
+| OUTMUX | BLUT | OUT |
+
+
+The site wire BLUT3\_O has 4 BEL pins:
+
+| BEL Name | Pin |
+|----------|------|
+| BLUT3 | O |
+| CARRY | SI |
+| FFMUX | BLUT |
+| OUTMUX | BLUT |
+
+The site wire B0 has 2 BEL pins:
+
+| BEL Name | Pin |
+|----------|-----|
+| B0 | B0 |
+| BLUT3 | I0 |
+
## Details
### Net routing summary
Each net start at the driver output/inout BEL pin. The BEL pin will be
connected to exactly 1 site wire. If the net sink can be reached within the
-site, then the net can use site PIPs (through a routing BEL) to reach a site
-wire connected to the input/inout BEL pin.
+site, then the net can use site PIPs to reach a site wire connected to the
+input/inout BEL pin.
If the net sink is in another site, then the net must first reach a site port
input BEL pin using site PIPs to reach the site wire connected to the site
@@ -162,7 +293,7 @@ of the alternative site types can be used at a time for a particular site.
A routing BEL represents statically configurable site routing by connecting a
site wire connected to one of the input BEL pins to the output BEL pin of
-the BEL. Routing BELs may only have 1 output BEL pin.
+the BEL. Routing BELs must have 1 output BEL pin.
#### Inverting routing BELs