# CODE_FIXES — YEEP-144 library

Two fixes to `YEEP144lib/src/YEEP144_BluetoothUART.c`, against the **1.2 release**.

Both are pre-existing issues that 1.2 does not address.

> **Already fixed in 1.2, not part of this change:** an earlier report covered
> `YEEP144_BluetoothUART_Init()` entering the RN4678's command mode and
> rebooting the module on every boot (by calling `SetStatusDelimiter()`
> unconditionally). 1.2 has removed that call from `Init()`, so no change is
> needed here. See "Suggested follow-up" below.

| # | Fix | Severity |
|---|---|---|
| 1 | `SetStatusDelimiter()` over-reads a stack buffer | Medium — undefined behaviour, and it sends garbage to the module |
| 2 | Three `-Wpointer-sign` warnings in the same function | Low — but they sit on the same lines as #1 |

---

## Fix 1 — SetStatusDelimiter over-reads a stack buffer

### Root cause

```c
uint8_t rxBuf[10];
...
char txBuf[8] = {0};
if(prefix == '\0' && postfix == '\0'){
    sprintf(txBuf, "SO,,%c",'\r');
}
...
HAL_UART_Transmit(&huart2, txBuf, sizeof(rxBuf), UART_POLL_TIMEOUT);
                                    ^^^^^^^^^^^^ rxBuf is uint8_t[10]
```

`rxBuf` is a **different, unrelated** buffer declared earlier in the same
function. This transmits **10 bytes from an 8-byte array** — a two-byte stack
over-read, so two bytes of stack garbage follow every `SO` command the module
receives.

1.2 no longer calls this function from `Init()`, so it is only reachable if an
application calls `YEEP144_BluetoothUART_SetStatusDelimiter()` directly. It is
still a public API function, and the over-read is undefined behaviour either way.

### Patch

```c
HAL_UART_Transmit(&huart2, (const uint8_t *)txBuf, (uint16_t)strlen(txBuf),
                  UART_POLL_TIMEOUT);
```

`strlen()` is the right length: it stops at the terminating NUL that
`sprintf()` wrote. `sizeof(txBuf)` would also fix the over-read, but would
still transmit the padding NULs that `sprintf()` left in the buffer.

---

## Fix 2 — Three pointer-sign warnings

### Symptom

```
warning: pointer targets in passing argument 2 of 'HAL_UART_Transmit' differ in
         signedness [-Wpointer-sign]
```

at three call sites in `SetStatusDelimiter()`.

### Root cause

`HAL_UART_Transmit()` takes `const uint8_t *`; the function passes `char *`
(two string literals, and `txBuf`).

### Patch

Cast at the three call sites:

```c
HAL_UART_Transmit(&huart2, (const uint8_t *)"$$$", 3, UART_POLL_TIMEOUT);
HAL_UART_Transmit(&huart2, (const uint8_t *)txBuf, (uint16_t)strlen(txBuf), UART_POLL_TIMEOUT);
HAL_UART_Transmit(&huart2, (const uint8_t *)"R,1", 3, UART_POLL_TIMEOUT);
```

With this, the file compiles warning-free.

---

## Suggested follow-up (not part of this change)

1.2 removed the module configuration from `Init()`. The capability itself is
still worth having, as an explicitly-named function rather than a side effect of
startup — e.g. `YEEP144_BluetoothUART_ConfigureModule()`, documented as taking
several seconds, entering the module's command mode, rebooting the module, and
therefore dropping any active connection.

---

## Files changed

| File | Change |
|---|---|
| `YEEP144lib/src/YEEP144_BluetoothUART.c` | Both fixes — 7 insertions, 3 deletions against `main` |

## Repository note

`Drivers/` (the vendored ST HAL and CMSIS) is not in this repository: it is
173 MB, of which 108 MB is ST's `.chm` user manuals. Fetch it from
STMicroelectronics/STM32CubeH5 if you need to build.