yeep-144-library/CODE_FIXES.md

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

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

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:

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.