PM0064

Programming sequence

Doc ID 16274 Rev 3

5/13

3

Programming sequence

Figure 4 describes how to program the STM8T141 device and then verify that your

programming was successful. Each state transition depends on the CS value and the clock

pulses applied to CX.

3.1

Programming mode entry

Programming mode entry (State_1) is the point from where you navigate to other

programming mode states. Each sequence in the following chapters uses the programming

mode entry sequence described in Table 2.

Refer to Figure 2 and Figure 3 for special sequences on CS (step 6) and CX (step 10).

Table 2.

Programming mode entry (State_1)

Step

Action

Explanation

1.

Make OUT input

Make the OUT pin an input.

2.

IC power ON

VDD = 5V

3.

CX = LOW

Start state of CX.

4.

CS = High

Start state of CS.

5.

Wait > 4ms

Wait for VREG to stabilize. Increase time if necessary to allow for a

larger capacitor on VREG.

6.

CS – 9 transitions

(starting with a

falling transition)

See Figure 2. The timing on CS is important. This timing is taken from

the center frequency. If the frequency is changed, or is not according to

specification, the timing must be scaled accordingly.

7.

Wait 100us

Wait for CS capacitor to discharge.

8.

CX = HIGH

CX is normally HIGH. Clocking is done with negative pulses.

9.

Wait 100us

Wait for CS capacitor to charge.

10.

CX - 9 double clock

18 negative pulses on CX to get into programming mode (State_0). All

CX clocks consist of two consecutive negative going pulses. See

Figure 3.

11.

CS = HIGH

CS = 1 required for transition from State_0 to State_1.

12.

CX - 1 double clock

Clock IC into State_1.