Problem to program KL05Z - reset_b oscillation

[R_L_]

Hi All,

     I'm having problems to program a KL05z . The board has only a 3.3v regulator  and a conection to SDA bus. I'm using  Keil + U-Multilink + KL05Z.

     I follow the guidelines of other posts (hold the reset_b to gnd during the powerup) but the MCU doesn't go to program mode.

     I read that this situation is normal before the first programming , but I don't know what i'm doing wrong.

I send a picture of the reset_b pin :

does exist a procedure to resolve this issue ?

Thanks in advance for your help.

Best Regards

Rodrigo

[Hui_Ma]

Hi Rodrigo,

Please check the RESET_b pin related circuit, if there with a 10K ohm pull-up resistor with RESET_b pin? And if you refer FRDM_KL05Z board to use  1UF capacitor? If so, could you try to modify the capacitor value to 0.1uF or just remove that capacitor.

Wish it helps.

B.R.

Ma Hui

[lachlanaudas]

Got  the same problem on a MKL04Z32VLF4,   debug works..    step's etc

but the  reset pin is oscillating!   pulling it hi with 100 Ohms resistor to 3.3v a pear’s to stop it oscillating ,   but,  cut it (while powered).. and oscillation is back !..  :smileysad:

Lachlan

[Hui_Ma]

Hi Lachlan,

"If flash is not programmed, the reset vector is 0xFFFF,FFFF , it is a illegal address, may cause reset. In reset sequence, reset pin will drive out"

So the waveform you observed is an expected behavior.

You can program KL04 chip with available image, then you could find the reset pin oscillating behavior gone.

Wish it helps.

Best regards,

Ma Hui