Method A: Cast each of the characters to uint32_t and be sure to completely
surround the casted value in parentheses.

Method B (probably better in my opinion): structure , union, or even just
an array of uint8_t.

On Saturday, August 11, 2018, Justin Richards <justin.richards@gmail.com>
wrote:

> Probably best posed in an arduino forum but hoping someone could pick an
> obvious mistake, steer me in the right direction or suggest a better way.
>
> I have generally avoided the << and >> operators but I thought they would
> be ideal to pack a 32bit variable with commands.
>
> So trying this
>
> uint32_t ds =3D ('D'<<24)|('C'<<16) |('B'<<8)|('A');
>
> when compiled for an ESP8266 target in arduino IDE and printed gives
>
> 0x44434241 as expected.
>
> when the target is UNO it produces
>
> 0x4241
>
> Doing this
>
>  uint32_t ds =3D 'D';
>   ds =3D (ds << 8)| 'C';
>   ds =3D (ds << 8)| 'B';
>   ds =3D (ds << 8)| 'A';
>
> for either target works ok.
>
> I have tried type casting (not sure that is the right phrase) like
>
> uint32_t ds =3D uint32_t('D'<<24)|uint32_t('C'<<16)
> |uint32_t('B'<<8)|uint32_t('A');
>
> But no joy for the uno target.
>
> The final goal is to construct SPI commands with a esp8266 master with a
> UNO slave.
>
> The following compiles and works fine for the esp8266 target but has the
> issues mentioned above for the UNO target.
>
> #define UNO1_ADDR uint32_t(uint32_t('U')|uint32_t('1'<<8)) //Address UNO1
> #define cmdREADPIN uint32_t(UNO1_ADDR | uint32_t('R'<<16))
> #define cmdWRITEPIN uint32_t((UNO1_ADDR | uint32_t('W'<<16))
> #define cmdREADPIN1 uint32_t(cmdREADPIN | uint32_t('1'<<24))
> #define cmdREADPIN2 uint32_t(cmdREADPIN | uint32_t('2'<<24))
> #define cmdREADPIN3 uint32_t(cmdREADPIN | uint32_t('3'<<24))
>
> Any tips?
>
> Justin
> --
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--=20
Jason White
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