Enable production of hex mfgimg files.
diff --git a/manifest/mfg_manifest.go b/manifest/mfg_manifest.go
index b7f00e8..da2d5e9 100644
--- a/manifest/mfg_manifest.go
+++ b/manifest/mfg_manifest.go
@@ -44,6 +44,7 @@
 	Version    string            `json:"version"`
 	Device     int               `json:"device"`
 	BinPath    string            `json:"bin_path"`
+	HexPath    string            `json:"hex_path"`
 	Bsp        string            `json:"bsp"`
 	Signatures []MfgManifestSig  `json:"signatures,omitempty"`
 	FlashAreas []flash.FlashArea `json:"flash_map"`
diff --git a/mfg/mfg.go b/mfg/mfg.go
index 3e29523..d3f5f93 100644
--- a/mfg/mfg.go
+++ b/mfg/mfg.go
@@ -6,7 +6,8 @@
 	"mynewt.apache.org/newt/util"
 )
 
-const MFG_IMG_FILENAME = "mfgimg.bin"
+const MFG_BIN_IMG_FILENAME = "mfgimg.bin"
+const MFG_HEX_IMG_FILENAME = "mfgimg.hex"
 const MANIFEST_FILENAME = "manifest.json"
 
 type Mfg struct {