J101 no serial data reception

Hi, i have bought 20 j101 seeed boards. I am trying to receive neo7m gps data on ttyTHS1 dev port for which i have connected gps with j101 as

pin 8 tx to rx of gps
Pin10 rx to tx of gps
Vcc to 5v
Gnd to gnd

Im reading serial data on minicom with settings baudrate 9600 and hardware flow control NO
N sofrware flow control NO.

Unfortunately out of 20 j101 boards, i can only recrive gps data on 3 boards with same above configurations.

Please help me what am i doing wrong.

make sure you tx and rx are connected correctly

controler to gps unit
tx to rx
rx to tx

next… gps may not start sending data immediatly… especially inside with a cold boot

these are the only ideas that could be hardware specific

last some gps use faster or slower speeds maybe try 4800 or 19200

also may check configuration i think neo7m has a windows app that connects thru the usb cable to access the settings in the chip

hope something helps