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Fix missing return code for ws2812_init() #1816

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Feb 24, 2017
Merged

Fix missing return code for ws2812_init() #1816

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4 changes: 3 additions & 1 deletion app/modules/ws2812.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ typedef struct {
// Init UART1 to be able to stream WS2812 data to GPIO2 pin
// If DUAL mode is selected, init UART0 to stream to TXD0 as well
// You HAVE to redirect LUA's output somewhere else
static void ws2812_init(lua_State* L) {
static int ws2812_init(lua_State* L) {
const int mode = luaL_optinteger(L, 1, MODE_SINGLE);
luaL_argcheck(L, mode == MODE_SINGLE || mode == MODE_DUAL, 1, "ws2812.SINGLE or ws2812.DUAL expected");

Expand Down Expand Up @@ -57,6 +57,8 @@ static void ws2812_init(lua_State* L) {
GPIO_REG_WRITE(GPIO_ENABLE_W1TC_ADDRESS, BIT2);
// Enable Function 2 for GPIO2 (U1TXD)
PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO2_U, FUNC_U1TXD_BK);

return 0;
}

// Stream data using UART1 routed to GPIO2
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11 changes: 7 additions & 4 deletions docs/en/modules/ws2812.md
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Original file line number Diff line number Diff line change
Expand Up @@ -15,14 +15,17 @@ through the serial port (it will be reconfigured to support WS2812-like
protocol). If you want to keep access to Lua's console, you will have to
use an other input channel like a TCP server (see [example](https://github.com/nodemcu/nodemcu-firmware/blob/master/examples/telnet.lua))

## ws2812.init(mode)
## ws2812.init()
Initialize UART1 and GPIO2, should be called once and before write().
Initialize UART0 (TXD0) too if `ws2812.MODE_DUAL` is set.

#### Syntax
`ws2812.init([mode])`

#### Parameters
- `mode` (optional) either `ws2812.MODE_SINGLE` (default if omitted) or `ws2812.MODE_DUAL`.
In `ws2812.MODE_DUAL` mode you will be able to handle two strips in parallel but will lose access
to Lua's serial console as it shares the same UART and PIN.
- `mode` (optional) either `ws2812.MODE_SINGLE` (default if omitted) or `ws2812.MODE_DUAL`

In `ws2812.MODE_DUAL` mode you will be able to handle two strips in parallel but will lose access to Lua's serial console as it shares the same UART and PIN.

#### Returns
`nil`
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Didn't you just change that in the code?

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The code change tells the caller of ws2812_init() that 0 results are returned on the stack aka nil. Before that, if told to print the result eg, the calling function would pick up a random value (since ws2812_init() didn't set a return value) and thus extract a random number of items from the stack, causing the crash.

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Got it, thanks for the explanation.

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