diff --git a/.gitignore b/.gitignore
index 28f22c0b..a1a839df 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@ env
 *.swp
 *.swo
 *.yaml
+!test_data/*
diff --git a/fpga_interchange/chip_info.py b/fpga_interchange/chip_info.py
index 87943f80..0666c843 100644
--- a/fpga_interchange/chip_info.py
+++ b/fpga_interchange/chip_info.py
@@ -19,6 +19,11 @@ class ConstraintType(Enum):
     TAG_REQUIRES = 1
 
 
+class ChainCoordinate(Enum):
+    X = 0
+    Y = 1
+
+
 class BelInfo():
     str_id_fields = ['ports']
     int_fields = ['types', 'wires']
@@ -646,6 +651,191 @@ def append_bba(self, bba, label_prefix):
             bba.u32(len(getattr(self, field)))
 
 
+class ChainPatternConfig():
+    def __init__(self, type, port):
+        self.type = type
+        self.port = port
+
+    def append_children_bba(self, bba, label_prefix):
+        pass
+
+    def append_bba(self, bba, label_prefix):
+        bba.str_id(self.type)
+        bba.str_id(self.port)
+
+
+class ChainPattern():
+    children_fields = [
+        'source', 'sink'
+    ]
+    children_types = [
+        'ChainPatternConfigPOD', 'ChainPatternConfigPOD'
+    ]
+
+    def __init__(self, source, sink):
+        self.source = ChainPatternConfig(source.type, source.port)
+        self.sink = ChainPatternConfig(sink.type, sink.port)
+
+    def field_label(self, label_prefix, field):
+        prefix = '{}.{}'.format(label_prefix, field)
+        return prefix
+
+    def append_children_bba(self, bba, label_prefix):
+        label = label_prefix
+
+        for field, field_type in zip(self.children_fields,
+                                     self.children_types):
+            prefix = self.field_label(label, field)
+            value = getattr(self, field)
+            value.append_children_bba(bba, prefix)
+
+            bba.label(prefix, field_type)
+            value.append_bba(bba, prefix)
+
+    def append_bba(self, bba, label_prefix):
+        for field in self.children_fields:
+            bba.ref(self.field_label(label_prefix, field))
+            bba.u32(1)
+
+
+class ChainDriverPortBel():
+    def __init__(self, name, bel):
+        self.name = name
+        self.bel = bel
+
+    def field_label(self, label_prefix, field):
+        prefix = '{}.{}.{}'.format(label_prefix, self.name, field)
+        return prefix
+
+    def append_children_bba(self, bba, label_prefix):
+        pass
+
+    def append_bba(self, bba, label_prefix):
+        bba.str_id(self.name)
+        bba.str_id(self.bel)
+
+
+class ChainDriver():
+    def __init__(self, ports, cells):
+        self.ports = []
+        self.cells = cells
+
+        for port in ports:
+            self.ports.append(ChainDriverPortBel(port.name, port.bel))
+
+    def field_label(self, label_prefix, field):
+        prefix = '{}.{}'.format(label_prefix, field)
+        return prefix
+
+    def append_children_bba(self, bba, label_prefix):
+        label = self.field_label(label_prefix, 'ports')
+        for port in self.ports:
+            port.append_children_bba(bba, label)
+
+        bba.label(label, 'ChainDriverPortBelPOD')
+        for port in self.ports:
+            port.append_bba(bba, label)
+
+        bba.label(self.field_label(label_prefix, 'cells'), 'constids')
+        for cell in self.cells:
+            bba.str_id(cell)
+
+    def append_bba(self, bba, label_prefix):
+        bba.ref(self.field_label(label_prefix, 'ports'))
+        bba.u32(len(self.ports))
+
+        bba.ref(self.field_label(label_prefix, 'cells'))
+        bba.u32(len(self.cells))
+
+
+class ChainCoordConfig():
+    def __init__(self, coord, step):
+        self.coord = ChainCoordinate[str(coord).upper()]
+        self.step = step
+
+    def append_children_bba(self, bba, label_prefix):
+        pass
+
+    def append_bba(self, bba, label_prefix):
+        bba.u8(self.coord.value)
+        bba.u8(self.step)
+        bba.u16(0)
+
+
+class BelChain():
+    children_fields = [
+        'patterns', 'coord_configs', 'chain_drivers'
+    ]
+    children_types = [
+        'ChainPatternPOD', 'ChainCoordConfigPOD', 'ChainDriverPOD'
+    ]
+
+    def __init__(self, name, patterns, sites, coord_configs, cells, chain_drivers):
+        # Chain name
+        self.name = name
+
+        # Chain patterns
+        self.patterns = []
+        for pattern in patterns:
+            self.patterns.append(ChainPattern(pattern.source, pattern.sink))
+
+        # Sites for which chain patterns apply
+        self.sites = sites
+
+        # Coordinates configurations
+        # which coordinate by what step should be incremented
+        self.coord_configs = []
+        for coord_config in coord_configs:
+            self.coord_configs.append(ChainCoordConfig(coord_config.coord, coord_config.step))
+
+        # Chain cells used in BEL chain
+        self.cells = cells
+
+        # Optional drivers of the cells used in BEL chain
+        self.chain_drivers = []
+        if chain_drivers is not None:
+            for driver in chain_drivers:
+                self.chain_drivers.append(ChainDriver(driver.ports, driver.cells))
+
+    def field_label(self, label_prefix, field):
+        prefix = '{}.{}.{}'.format(label_prefix, self.name, field)
+        return prefix
+
+    def append_children_bba(self, bba, label_prefix):
+        label = label_prefix
+
+        bba.label(self.field_label(label_prefix, 'sites'), 'constids')
+        for site in self.sites:
+            bba.str_id(site)
+
+        bba.label(self.field_label(label_prefix, 'cells'), 'constids')
+        for cell in self.cells:
+            bba.str_id(cell)
+
+        for field, field_type in zip(self.children_fields,
+                                     self.children_types):
+            prefix = self.field_label(label, field)
+            for value in getattr(self, field):
+                value.append_children_bba(bba, prefix)
+
+            bba.label(prefix, field_type)
+            for value in getattr(self, field):
+                value.append_bba(bba, prefix)
+
+    def append_bba(self, bba, label_prefix):
+        bba.str_id(self.name)
+
+        bba.ref(self.field_label(label_prefix, 'sites'))
+        bba.u32(len(self.sites))
+
+        bba.ref(self.field_label(label_prefix, 'cells'))
+        bba.u32(len(self.cells))
+
+        for field in self.children_fields:
+            bba.ref(self.field_label(label_prefix, field))
+            bba.u32(len(getattr(self, field)))
+
+
 class PackagePin():
     def __init__(self):
         self.package_pin = ''
@@ -1053,6 +1243,7 @@ def __init__(self):
         self.packages = []
         self.wire_types = []
         self.global_cells = []
+        self.bel_chains = []
 
         # str, constids
         self.bel_buckets = []
@@ -1068,7 +1259,7 @@ def append_bba(self, bba, label_prefix):
 
         children_fields = [
             'tile_types', 'sites', 'tiles', 'nodes', 'packages', 'wire_types',
-            'global_cells', 'macros', 'macro_rules'
+            'global_cells', 'macros', 'macro_rules', 'bel_chains'
         ]
         children_types = [
             'TileTypeInfoPOD',
@@ -1080,6 +1271,7 @@ def append_bba(self, bba, label_prefix):
             'GlobalCellPOD',
             'MacroPOD',
             'MacroExpansionPOD',
+            'BelChainPOD',
         ]
         for field, field_type in zip(children_fields, children_types):
             prefix = '{}.{}'.format(label, field)
diff --git a/fpga_interchange/nextpnr.py b/fpga_interchange/nextpnr.py
index 2bbe4124..87a934ad 100644
--- a/fpga_interchange/nextpnr.py
+++ b/fpga_interchange/nextpnr.py
@@ -81,5 +81,5 @@ def pop(self):
 
     def check_labels(self):
         refs_and_labels = self.refs & self.labels
-        assert len(refs_and_labels) == len(self.refs)
-        assert len(refs_and_labels) == len(self.labels)
+        assert len(refs_and_labels) == len(self.refs), "{} vs. {}".format(len(refs_and_labels), len(self.refs))
+        assert len(refs_and_labels) == len(self.labels), "{} vs. {}".format(len(refs_and_labels), len(self.labels))
diff --git a/fpga_interchange/populate_chip_info.py b/fpga_interchange/populate_chip_info.py
index 24287583..79809fcd 100644
--- a/fpga_interchange/populate_chip_info.py
+++ b/fpga_interchange/populate_chip_info.py
@@ -16,8 +16,8 @@
         TileWireRef, CellBelMap, ParameterPins, CellBelPin, ConstraintTag, \
         CellConstraint, ConstraintType, Package, PackagePin, LutCell, \
         LutElement, LutBel, CellParameter, DefaultCellConnections, DefaultCellConnection, \
-        WireType, Macro, MacroNet, MacroPortInst, MacroCellInst, MacroExpansion, MacroParamMapRule, MacroParamRuleType, MacroParameter, GlobalCell, GlobalCellPin
-
+        WireType, Macro, MacroNet, MacroPortInst, MacroCellInst, MacroExpansion, \
+        MacroParamMapRule, MacroParamRuleType, MacroParameter, GlobalCell, GlobalCellPin, BelChain
 from fpga_interchange.constraints.model import Tag, Placement, \
         ImpliesConstraint, RequiresConstraint
 from fpga_interchange.constraint_generator import ConstraintPrototype
@@ -1835,6 +1835,19 @@ def populate_chip_info(device, constids, device_config):
         assert lut_element.site not in lut_elements
         lut_elements[lut_element.site] = LutElementsEmitter(lut_element.luts)
 
+    bel_chains = {}
+    for bel_chain in device.device_resource_capnp.belChainsDefinitions.belChains:
+        assert bel_chain.name not in bel_chains.keys()
+        drivers_present = bel_chain.which() == "chainDrivers"
+        bel_chains[bel_chain.name] = BelChain(bel_chain.name,
+                                            bel_chain.patterns,
+                                            bel_chain.sites,
+                                            bel_chain.coordConfigs,
+                                            bel_chain.cells,
+                                            bel_chain.chainDrivers if drivers_present else None)
+
+        chip_info.bel_chains.append(bel_chains[bel_chain.name])
+
     for tile_type_index, tile_type in enumerate(
             device.device_resource_capnp.tileTypeList):
         flattened_tile_type = FlattenedTileType(
diff --git a/test_data/series7_bel_chains.yaml b/test_data/series7_bel_chains.yaml
new file mode 100644
index 00000000..30809a31
--- /dev/null
+++ b/test_data/series7_bel_chains.yaml
@@ -0,0 +1,26 @@
+belChains:
+- name: carryChain
+  patterns:
+    - {source: {type: "CARRY4", port: "CO[3]"}, sink: {type: "CARRY4", port: "CI"}}
+  sites:
+    - SLICEL
+    - SLICEM
+  cells:
+    - CARRY4
+  chainDrivers: # Place driver cell of S port to a proper BEL
+  - ports:
+    - name: S[0]
+      bel: AFF
+    - name: S[1]
+      bel: BFF
+    - name: S[2]
+      bel: CFF
+    - name: S[3]
+      bel: DFF
+    cells:
+      - FDRE
+      - FDSE
+      - FDCE
+  coordConfigs:
+    - {coord: y, step: -1} # Default
+    - {coord: y, step: -2} # When crossing clock region