Datasheet

TMC429 DATASHEET (v. 1.07 / 2012-AUG-01) 45

binary datagram specification : hexadecimal datagram

%10000000----------000101–010000 : $80000510

%10000010----------000011–000100 : $82000304

%10000100----------000110–000010 : $84000602

%10000110----------001101–010000 : $86000D10

%10001000----------001011–001100 : $88000B0C

%10001010----------101110–001010 : $8°002E0A

%10001100----------000101–010000 : $8c000510

%10001110----------000011–000100 : $8e000304

%10010000----------000110–000010 : $90000602

%10010010----------001101–010000 : $92000D10

%10010100----------001011–001100 : $94000B0C

%10010110----------101110–001010 : $96002E0A

%10011000----------000101–000111 : $98000507

%10011010----------000011–000100 : $9°000304

%10011100----------000110–000010 : $9c000602

%10011110----------001101–001111 : $9e000D0F

%10100000----------001011–001100 : $a0000B0C

%10100010----------101110–001010 : $a2002E0A

Table 12-3: Configuration datagram sequence for the example (with ‘-‘ (don’t cares))

13 Initialization of the Micro Step Look-Up-Table

The TMC429 provides a look-up-table (LUT) of 64 values of 6 bit for micro stepping. The micro step

LUT can be adapted by storing an arbitrary quarter period of a periodic function to match individual

stepper motor characteristics. It is common to use one period of a sine wave function for micro

stepping. With that function, the current of one phase is driven with the sine function whereas the other

phase is driven with the cosine function.

To initialize the LUT for micro stepping one simply has to load a quarter sine wave period into the

micro step LUT. Two successive values of the sine wave function are included in one datagram similar

to the primary signal code words for the stepper motor driver chain configuration. The TMC429

automatically expands the quarter sine wave period to a full sine and cosine function. The necessary

data values y(i) to represent a ¼ sine wave period for the micro step LUT are defined by

y(i) = int[ ½ + 64 * sin(¼ * 2 *  * i / 64) ] with i = { 0, 1, 2, 3, ..., 60, 61, 62, 63 },

where the conditional replacement y(i) := 63 for y(i) > 63 has to be done. The last five values (which

are calculated to be 64) have to be replaced by 63. With this replacement one finally gets y(i) = { 0, 2,

3, 5, 6, 8, 9, 11, 12, 14, 16, 17, 19, 20, 22, 23, 24, 26, 27, 29, 30, 32, 33, 34, 36, 37, 38, 39, 41, 42, 43,

44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 59, 60, 60, 61, 61, 62, 62, 62, 63, 63,

63, 63, 63, 63, 63, 63 }.

Hint: The power-on reset default initialization of the TMC429 sine wave look-up table is with offset for

TMC236/TMC239/TMC246/TMC249 with mixed decay control = One (ON).

Pleses refer TMC260/TMC261/TMC262 datasheet in case of SPI motion control. For step/direction

control the TMC260/TMC261/TMC262 have their own optimized build-in sine wave look-up table.