LPC5536 - SPI MISO is pulled high by board

[fr0stw1ng]

Hi, as the title states the MISO pin in multiple connector positions for the HS SPI (SPI8) 
are pulled high by board and stay there even after SPI master init is called by all example programs including: 
* spi_HS_LSPI_dma_b2b_transfer_master
* spi_polling_b2b_transfer_master

Also tested flexcom2  as SPI without merit.


General result: Misopin is always pulled high from the moment the board is powered. 
The pin stays high even after calling SPI_MasterInit() function while other related pins get pulled to their setting. IE  CLK, MOSI pulled down and SS stays HIGH untill transfer is started. 
 This results in miso always being read as 0xFF when reading a byte even when miso pin is disconnected.
Unconnected slave miso shows actual data from the slave device. 

See results in Logic analyser below. 

2bytes, miso with or without slave connected to miso pin. miso ALWAYS high.2 bytes, miso data read from slave while not connected to LPC5536SPI pins before and after SPI_masterInit()


What am i missing here? 
tested an other board with same code without results. 

[fr0stw1ng]

Hi, 

I've tested P1_3 miso on both J7 and all the pins of J92 using a logic analyzer. 
None of the tested pins toggled. pin10 of J92 still stays high. 
For good measure I also tested with JP48 in different positions.
The used code was supplied in previous post, so led and P1_3 should toggle parallel with the led.
The parallel toggle was verified using multiple other pins not related to P1_3.

As you can see in the picture, jp57 was populated and bridged. 

kind regards

[xiangjun_rong]

Hi,

is it possible to use a scope and test the pin logic?

BR

XiangJun Rong

[fr0stw1ng]

Hi 

Sorry for my late reply, i had a week off. 

I should have specified, All of my last tests were done with both logic analyser and scope. 
as previously mentioned i also checked the parallel pin logic of other pins somewhere in the range of P1,20- 26. These pins displayed the same functionality as the rgb led ( as programmed). 

[fr0stw1ng]

Hi, 


i did not connect an led to p1,3 
what i did is add this to line 67, rest of supplied code was unchanged, for the fun of it i also checked without changes to your code, which in this case the change i made should not break the toggle of pin 1,3 ...
expected result: the led on the board & pin 1,3 would change state every 1 second.
actual result: led flashes & pin1,3 stays high.

while (1)
{
/* Delay 1000 ms */
SysTick_DelayTicks(1000U);
GPIO_PortToggle(GPIO, BOARD_LED_PORT, 1u << BOARD_LED_PIN);
GPIO_PortToggle(GPIO,1,0x08);
}


kind regards, 

Bonus info: 
we just checked the board from unopened and unused board and 
even with original code that comes supplied with the board pin1,3 is high while all other SPI related pins are pulled low. 


P1,3