# NTAG5Link Config Verification via uFR Zero

**Date**: 2026-03-03
**Status**: Tool written, reader connection blocked

## Goal

Read-only verification that the NTAG5Link Click board's configuration matches xblink requirements, using the Digital Logic uFR Zero Multi-ISO reader.

## Tool

`tools/ntag5_config_check.py` — Python script using uFCoder library (ctypes) in ISO15693 transparent mode.

Features:
- ISO15693 INVENTORY to discover all tags by UID
- Addressed mode for all config reads (supports multiple tags in field)
- Reads CONFIG block (0x37) and EH/ED CONFIG block (0x3D)
- NXP system info for interface type verification
- Checks against xblink expected config values

## Expected Config

| Setting | Expected | Config Location |
|---------|----------|----------------|
| EH mode | low_field_strength | CONFIG byte 0, bits 3:2 = 10 |
| Use case | i2c_slave | CONFIG byte 1, bits 5:4 = 00 |
| SRAM enabled | true | CONFIG byte 1, bit 1 = 1 |
| Arbiter mode | sram_passthrough | CONFIG byte 1, bits 3:2 = 10 |
| EH enable | true | EH_CONFIG byte 0, bit 0 = 1 |
| EH voltage | 3.0V | EH_CONFIG byte 0, bits 2:1 = 10 |

## Reader Connection Issue

**Problem**: uFCoder library returns `UFR_TIMEOUT_ERR` (0x1002) for all `ReaderOpenEx` parameter combinations.

**USB device**: `10c4:ea60` — Silicon Labs CP2102 USB to UART Bridge Controller, iSerial "0001". Generic descriptor, no D-Logic branding in USB strings.

**Raw serial investigation**:
- At 1 Mbps (expected uFR baud): responds with `00 80` (2 bytes) — not a valid uFR protocol frame (expected 6+ bytes with `0x55...0xAA` framing)
- At 115200 bps: returns ASCII shell commands mentioning "systemctl", "proxmark3" paths
- At 250 Kbps: returns structured but unrecognized data

**Possible causes**:
1. Device may not be a uFR Zero — the CP210x bridge has generic descriptors
2. Reader firmware may need updating
3. Reader may be in a non-standard mode
4. Different hardware variant requiring different protocol

**Next steps**:
1. Physically verify the device is indeed the uFR Zero (check labels, LEDs)
2. Try the D-Logic `ufr_online` Windows utility to confirm reader identity
3. If confirmed as uFR Zero, check firmware version and update if needed
4. Alternative: use the ACR1552 PCSC reader with ntag5sensor directly (requires porting the reader to share the field with NTAG5 Click)

## Fallback Plan: ntag5sensor + ACR1552

If the uFR Zero connection cannot be resolved, use the existing ntag5sensor Python tooling with the ACR1552 PCSC reader:

```python
# From ntag5sensor — already has full config read/write support
chip = NTAG5Link(reader)
config = chip.get_config_info()
eh_config = chip.get_eh_ed_config_info()
```

The ACR1552 is already proven with ntag5sensor. Only change needed: physically position the ACR1552 over the NTAG5 Click board instead of the uFR Zero.

## Config Change Plan (if mismatches found)

Use ntag5sensor's write functions (via ACR1552 or adapted for uFR Zero):

```python
# Set I2C slave mode + SRAM passthrough + SRAM enable
chip.write_config1(
    sram_enable=True,
    arbiter_mode=NXP_CONFIG_1_ARBITER_MODE_SRAM_PASSTHROUGH,
    use_case=NXP_CONFIG_1_USE_CASE_CONF_I2C_SLAVE
)

# Set EH: 3.0V, enabled, current limit TBD
chip.write_eh_ed_config(
    enable=True,
    voltage=NXP_EH_CONFIG_EH_VOUT_V_SEL_3_0,
    current=NXP_EH_CONFIG_EH_VOUT_I_SEL_12_5,  # max for testing
    ed_config=NXP_ED_CONFIG_NFC_FIELD_DETECT
)

# Set EH mode in CONFIG byte 0
chip.write_config0(eh_mode=NXP_CONFIG_0_EH_MODE_LOW_FIELD_STRENGTH)
```