Updates

device_server.py

@@ -27,7 +27,7 @@ REGISTER_COMMANDS = [
 # ---------------------------------------------------------------------------
 # SN65DSI83 I2C configuration
 # ---------------------------------------------------------------------------
-SN65_I2C_BUS  = 2      # i2c-2 on i.MX 8M Mini — change if bridge is on a different bus
+SN65_I2C_BUS  = 4      # i2c-4 on this board
 SN65_I2C_ADDR = 0x2C   # SN65DSI83 fixed 7-bit I2C address
 
 # Known Samsung DSIM register names (base 0x32E10000, i.MX 8M Mini)
@@ -124,25 +124,28 @@ def get_registers():
     }), 200
 
 
-def _i2c_read_byte(bus: int, addr: int, reg: int) -> int | None:
-    """Read one byte from an I2C device using i2cget. Returns None on failure."""
+def _i2c_read_byte(bus: int, addr: int, reg: int) -> tuple[int | None, str]:
+    """Read one byte via i2cget. Returns (value, "") on success or (None, error_str) on failure."""
     try:
         result = subprocess.run(
-            ["i2cget", "-y", str(bus), f"0x{addr:02x}", f"0x{reg:02x}"],
+            ["i2cget", "-y", "-f", str(bus), f"0x{addr:02x}", f"0x{reg:02x}"],
             capture_output=True, text=True, timeout=3
         )
         if result.returncode == 0:
-            return int(result.stdout.strip(), 16)
-    except Exception:
-        pass
-    return None
+            return int(result.stdout.strip(), 16), ""
+        stderr = result.stderr.strip() or f"exit code {result.returncode}"
+        return None, stderr
+    except FileNotFoundError:
+        return None, "i2cget not found in PATH"
+    except Exception as e:
+        return None, str(e)
 
 
 @app.route("/sn65_registers", methods=["GET"])
 def get_sn65_registers():
     """Read SN65DSI83 CSR 0x0A (PLL/CLK status) and 0xE5 (error flags) via I2C."""
-    csr_0a = _i2c_read_byte(SN65_I2C_BUS, SN65_I2C_ADDR, 0x0A)
-    csr_e5 = _i2c_read_byte(SN65_I2C_BUS, SN65_I2C_ADDR, 0xE5)
+    csr_0a, err_0a = _i2c_read_byte(SN65_I2C_BUS, SN65_I2C_ADDR, 0x0A)
+    csr_e5, err_e5 = _i2c_read_byte(SN65_I2C_BUS, SN65_I2C_ADDR, 0xE5)
 
     regs   = {}
     errors = []
@@ -151,10 +154,10 @@ def get_sn65_registers():
         regs["csr_0a"] = {
             "value":    f"0x{csr_0a:02x}",
             "pll_lock": bool(csr_0a & 0x80),   # bit 7: PLL_EN_STAT (powered + locked)
-            "clk_det":  bool(csr_0a & 0x40),   # bit 6: high-speed CLK lane detected
+            "clk_det":  bool(csr_0a & 0x08),   # bit 3: CHA_CLK_DET (HS clock detected)
         }
     else:
-        errors.append("CSR 0x0A: i2cget failed")
+        errors.append(f"CSR 0x0A: {err_0a}")
 
     if csr_e5 is not None:
         regs["csr_e5"] = {
@@ -167,7 +170,7 @@ def get_sn65_registers():
             "cha_crc_err":     bool(csr_e5 & 0x40),
         }
     else:
-        errors.append("CSR 0xE5: i2cget failed")
+        errors.append(f"CSR 0xE5: {err_e5}")
 
     return jsonify({
         "i2c_bus":   SN65_I2C_BUS,